diff --git a/pkg/ccn-lite/Makefile.include b/pkg/ccn-lite/Makefile.include
index bab9bba358..c7f9313396 100644
--- a/pkg/ccn-lite/Makefile.include
+++ b/pkg/ccn-lite/Makefile.include
@@ -1,7 +1,8 @@
-INCLUDES += -I$(PKGDIRBASE)/ccn-lite/src/ccnl-riot/include
-INCLUDES += -I$(PKGDIRBASE)/ccn-lite/src/ccnl-core/include
-INCLUDES += -I$(PKGDIRBASE)/ccn-lite/src/ccnl-pkt/include
-INCLUDES += -I$(PKGDIRBASE)/ccn-lite/src/ccnl-fwd/include
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/ccn-lite/src/ccnl-riot/include
+INCLUDES += -isystem$(PKGDIRBASE)/ccn-lite/src/ccnl-core/include
+INCLUDES += -isystem$(PKGDIRBASE)/ccn-lite/src/ccnl-pkt/include
+INCLUDES += -isystem$(PKGDIRBASE)/ccn-lite/src/ccnl-fwd/include
 
 CFLAGS += -DCCNL_RIOT
 ARCHIVES += $(BINDIR)/ccn-lite.a
diff --git a/pkg/cmsis/Makefile.include b/pkg/cmsis/Makefile.include
index faef2c8f65..d8ed837d4f 100644
--- a/pkg/cmsis/Makefile.include
+++ b/pkg/cmsis/Makefile.include
@@ -1,14 +1,15 @@
-INCLUDES += -I$(PKGDIRBASE)/cmsis/CMSIS/Core/Include
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/cmsis/CMSIS/Core/Include
 
 ifneq (,$(filter cmsis-dsp,$(USEMODULE)))
-  INCLUDES += -I$(PKGDIRBASE)/cmsis/CMSIS/DSP/Include
-  INCLUDES += -I$(PKGDIRBASE)/cmsis/CMSIS/DSP/PrivateInclude
+  INCLUDES += -isystem$(PKGDIRBASE)/cmsis/CMSIS/DSP/Include
+  INCLUDES += -isystem$(PKGDIRBASE)/cmsis/CMSIS/DSP/PrivateInclude
   CFLAGS += -DARM_CPU="cortex-m4"
 endif
 
 ifneq (,$(filter cmsis-nn,$(USEMODULE)))
-  INCLUDES += -I$(PKGDIRBASE)/cmsis/CMSIS/DSP/Include
-  INCLUDES += -I$(PKGDIRBASE)/cmsis/CMSIS/NN/Include
+  INCLUDES += -isystem$(PKGDIRBASE)/cmsis/CMSIS/DSP/Include
+  INCLUDES += -isystem$(PKGDIRBASE)/cmsis/CMSIS/NN/Include
   # Required for some basic math functions
   CFLAGS += -Wno-sign-compare
 endif
diff --git a/pkg/cn-cbor/Makefile.include b/pkg/cn-cbor/Makefile.include
index 026202fe34..db4d456037 100644
--- a/pkg/cn-cbor/Makefile.include
+++ b/pkg/cn-cbor/Makefile.include
@@ -1,4 +1,5 @@
-INCLUDES += -I$(PKGDIRBASE)/cn-cbor/include
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/cn-cbor/include
 
 #enable context pointer
 CFLAGS += -DUSE_CBOR_CONTEXT
diff --git a/pkg/cryptoauthlib/Makefile.include b/pkg/cryptoauthlib/Makefile.include
index 2acafea0c6..05cc3fe643 100644
--- a/pkg/cryptoauthlib/Makefile.include
+++ b/pkg/cryptoauthlib/Makefile.include
@@ -1,30 +1,31 @@
 PKG_SOURCE_DIR ?= $(PKGDIRBASE)/cryptoauthlib
 PKG_TESTINCLDIR = $(PKG_SOURCE_DIR)/test
 
-INCLUDES += -I$(PKG_SOURCE_DIR)
-INCLUDES += -I$(PKG_SOURCE_DIR)/lib
-INCLUDES += -I$(PKG_SOURCE_DIR)/app
-INCLUDES += -I$(PKG_SOURCE_DIR)/lib/calib
-INCLUDES += -I$(RIOTPKG)/cryptoauthlib/include
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKG_SOURCE_DIR)
+INCLUDES += -isystem$(PKG_SOURCE_DIR)/lib
+INCLUDES += -isystem$(PKG_SOURCE_DIR)/app
+INCLUDES += -isystem$(PKG_SOURCE_DIR)/lib/calib
+INCLUDES += -isystem$(RIOTPKG)/cryptoauthlib/include
 
 ifneq (,$(filter psa_crypto, $(USEMODULE)))
   DIRS += $(RIOTPKG)/cryptoauthlib/psa_atca_driver
-  INCLUDES += -I$(RIOTBASE)/sys/psa_crypto/include
+  INCLUDES += -isystem$(RIOTBASE)/sys/psa_crypto/include
 endif
 
 DIRS += $(RIOTPKG)/cryptoauthlib/contrib
 ARCHIVES += $(BINDIR)/cryptoauthlib.a
 
 ifneq (,$(filter cryptoauthlib_test,$(USEMODULE)))
-  INCLUDES += -I$(PKG_TESTINCLDIR)
-  INCLUDES += -I$(PKG_TESTINCLDIR)/jwt
-  INCLUDES += -I$(PKG_TESTINCLDIR)/tng
-  INCLUDES += -I$(PKG_TESTINCLDIR)/atcacert
-  INCLUDES += -I$(PKG_TESTINCLDIR)/api_atcab
-  INCLUDES += -I$(PKG_TESTINCLDIR)/api_calib
-  INCLUDES += -I$(PKG_TESTINCLDIR)/api_crypto
-  INCLUDES += -I$(PKG_TESTINCLDIR)/vectors
-  INCLUDES += -I$(PKG_SOURCE_DIR)/third_party/unity
+  INCLUDES += -isystem$(PKG_TESTINCLDIR)
+  INCLUDES += -isystem$(PKG_TESTINCLDIR)/jwt
+  INCLUDES += -isystem$(PKG_TESTINCLDIR)/tng
+  INCLUDES += -isystem$(PKG_TESTINCLDIR)/atcacert
+  INCLUDES += -isystem$(PKG_TESTINCLDIR)/api_atcab
+  INCLUDES += -isystem$(PKG_TESTINCLDIR)/api_calib
+  INCLUDES += -isystem$(PKG_TESTINCLDIR)/api_crypto
+  INCLUDES += -isystem$(PKG_TESTINCLDIR)/vectors
+  INCLUDES += -isystem$(PKG_SOURCE_DIR)/third_party/unity
 endif
 
 PSEUDOMODULES += psa_secure_element_ateccx08a
diff --git a/pkg/driver_atwinc15x0/Makefile.include b/pkg/driver_atwinc15x0/Makefile.include
index 280d4fc67a..4d0a178a80 100644
--- a/pkg/driver_atwinc15x0/Makefile.include
+++ b/pkg/driver_atwinc15x0/Makefile.include
@@ -1 +1,2 @@
-INCLUDES += -I$(PKGDIRBASE)/driver_atwinc15x0/src
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/driver_atwinc15x0/src
diff --git a/pkg/driver_bme680/Makefile.include b/pkg/driver_bme680/Makefile.include
index 91522faa40..1c5aa51a50 100644
--- a/pkg/driver_bme680/Makefile.include
+++ b/pkg/driver_bme680/Makefile.include
@@ -1,4 +1,5 @@
-INCLUDES += -I$(PKGDIRBASE)/driver_bme680
-INCLUDES += -I$(RIOTPKG)/driver_bme680/include
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/driver_bme680
+INCLUDES += -isystem$(RIOTPKG)/driver_bme680/include
 
 DIRS += $(RIOTPKG)/driver_bme680/contrib
diff --git a/pkg/driver_cryptocell_310/Makefile.include b/pkg/driver_cryptocell_310/Makefile.include
index a6424efe04..009ec9a338 100644
--- a/pkg/driver_cryptocell_310/Makefile.include
+++ b/pkg/driver_cryptocell_310/Makefile.include
@@ -1,5 +1,6 @@
-INCLUDES += -I$(PKGDIRBASE)/driver_cryptocell_310/include
-INCLUDES += -I$(RIOTPKG)/driver_cryptocell_310/include
+# using -isystem instead of -I to avoid warnings on the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/driver_cryptocell_310/include
+INCLUDES += -isystem$(RIOTPKG)/driver_cryptocell_310/include
 DIRS += $(RIOTPKG)/driver_cryptocell_310/contrib
 
 ARCHIVES += $(PKGDIRBASE)/driver_cryptocell_310/libnrf_cc310_0.9.13.a
diff --git a/pkg/driver_sen5x/Makefile.include b/pkg/driver_sen5x/Makefile.include
index 45ba6ae1a2..6ec7ca695e 100644
--- a/pkg/driver_sen5x/Makefile.include
+++ b/pkg/driver_sen5x/Makefile.include
@@ -1 +1,2 @@
-INCLUDES += -I$(PKGDIRBASE)/driver_sen5x
\ No newline at end of file
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/driver_sen5x
diff --git a/pkg/driver_sx126x/Makefile.include b/pkg/driver_sx126x/Makefile.include
index 1dc9126938..b5f9164f7f 100644
--- a/pkg/driver_sx126x/Makefile.include
+++ b/pkg/driver_sx126x/Makefile.include
@@ -1,3 +1,4 @@
-INCLUDES += -I$(PKGDIRBASE)/driver_sx126x/src
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/driver_sx126x/src
 
 DIRS += $(RIOTBASE)/pkg/driver_sx126x/contrib
diff --git a/pkg/edhoc-c/Makefile.include b/pkg/edhoc-c/Makefile.include
index ebd90a09f1..c1c9f49707 100644
--- a/pkg/edhoc-c/Makefile.include
+++ b/pkg/edhoc-c/Makefile.include
@@ -1,6 +1,7 @@
-INCLUDES += -I$(PKGDIRBASE)/EDHOC-C/include \
-            -I$(PKGDIRBASE)/EDHOC-C/src \
-            -I$(RIOTBASE)/pkg/edhoc-c/include \
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/EDHOC-C/include \
+            -isystem$(PKGDIRBASE)/EDHOC-C/src \
+            -isystem$(RIOTBASE)/pkg/edhoc-c/include \
             #
 
 ifneq (,$(filter edhoc-c_crypto_wolfssl,$(USEMODULE)))
diff --git a/pkg/etl/Makefile.include b/pkg/etl/Makefile.include
index a8ae45fa15..e1c075b8d4 100644
--- a/pkg/etl/Makefile.include
+++ b/pkg/etl/Makefile.include
@@ -1,5 +1,15 @@
-INCLUDES += -I$(PKGDIRBASE)/etl/include
-INCLUDES += -I$(RIOTPKG)/etl/config
+# Hack: On LLVM, use `-isystem` instead of -I to ignore warnings about the
+#       package's headers. On g++ (at least the AVR variant), `-system` is C
+#       only. But luckily, g++ does not emit the warnings we need to ignore
+#       anyway.
+
+ifeq (llvm,$(TOOLCHAIN))
+  INCLUDES += -isystem$(PKGDIRBASE)/etl/include
+  INCLUDES += -isystem$(RIOTPKG)/etl/config
+else
+  INCLUDES += -I$(PKGDIRBASE)/etl/include
+  INCLUDES += -I$(RIOTPKG)/etl/config
+endif
 
 # There's nothing to build in this package, it's used as a header only library.
 # So it's declared as a pseudo-module
diff --git a/pkg/gecko_sdk/Makefile.include b/pkg/gecko_sdk/Makefile.include
index 54d410cf96..b3eb610ec8 100644
--- a/pkg/gecko_sdk/Makefile.include
+++ b/pkg/gecko_sdk/Makefile.include
@@ -1,16 +1,17 @@
-INCLUDES += -I$(PKGDIRBASE)/gecko_sdk/dist/common/inc
-INCLUDES += -I$(PKGDIRBASE)/gecko_sdk/dist/emlib/inc
-INCLUDES += -I$(PKGDIRBASE)/gecko_sdk/dist/emlib-extra/inc
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/gecko_sdk/dist/common/inc
+INCLUDES += -isystem$(PKGDIRBASE)/gecko_sdk/dist/emlib/inc
+INCLUDES += -isystem$(PKGDIRBASE)/gecko_sdk/dist/emlib-extra/inc
 
 ifneq (,$(filter gecko_sdk_librail,$(USEMODULE)))
   ARCHIVES += $(BINDIR)/gecko_sdk_librail.a
-  INCLUDES += -I$(PKGDIRBASE)/gecko_sdk/dist/radio/rail_lib/common
-  INCLUDES += -I$(PKGDIRBASE)/gecko_sdk/dist/radio/rail_lib/chip/efr32/$(EFM32_LIBRAIL_HEADER_NAME)
+  INCLUDES += -isystem$(PKGDIRBASE)/gecko_sdk/dist/radio/rail_lib/common
+  INCLUDES += -isystem$(PKGDIRBASE)/gecko_sdk/dist/radio/rail_lib/chip/efr32/$(EFM32_LIBRAIL_HEADER_NAME)
 endif
 
 ifneq (,$(filter gecko_sdk_librail_pa,$(USEMODULE)))
-  INCLUDES += -I$(PKGDIRBASE)/gecko_sdk/dist/radio/rail_lib/plugin/pa-conversions
-  INCLUDES += -I$(PKGDIRBASE)/gecko_sdk/dist/radio/rail_lib/plugin/pa-conversions/$(EFM32_LIBRAIL_PA_HEADER_NAME)/config
+  INCLUDES += -isystem$(PKGDIRBASE)/gecko_sdk/dist/radio/rail_lib/plugin/pa-conversions
+  INCLUDES += -isystem$(PKGDIRBASE)/gecko_sdk/dist/radio/rail_lib/plugin/pa-conversions/$(EFM32_LIBRAIL_PA_HEADER_NAME)/config
 endif
 
 ifeq ($(CPU_CORE),cortex-m33)
diff --git a/pkg/libcose/Makefile.include b/pkg/libcose/Makefile.include
index ebe77d953c..18bb47e25d 100644
--- a/pkg/libcose/Makefile.include
+++ b/pkg/libcose/Makefile.include
@@ -1,5 +1,6 @@
-INCLUDES += -I$(PKGDIRBASE)/libcose/include \
-            -I$(RIOTBASE)/pkg/libcose/include \
+# using -isystem to avoid warnings about these headers
+INCLUDES += -isystem$(PKGDIRBASE)/libcose/include \
+            -isystem$(RIOTBASE)/pkg/libcose/include \
             #
 
 CFLAGS += -DUSE_CBOR_CONTEXT
diff --git a/pkg/lorabasics/Makefile.include b/pkg/lorabasics/Makefile.include
index ff41b54cc7..9f772768cc 100644
--- a/pkg/lorabasics/Makefile.include
+++ b/pkg/lorabasics/Makefile.include
@@ -1,4 +1,5 @@
-INCLUDES += -I$(PKGDIRBASE)/lorabasicsmodem \
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/lorabasicsmodem \
             #
 
 ifneq (,$(filter lorabasics_driver_sx1280_hal,$(USEMODULE)))
diff --git a/pkg/lua/Makefile.include b/pkg/lua/Makefile.include
index ab9d3759b2..6d1169056d 100644
--- a/pkg/lua/Makefile.include
+++ b/pkg/lua/Makefile.include
@@ -1,3 +1,4 @@
-INCLUDES += -I$(PKGDIRBASE)/lua
-INCLUDES += -I$(RIOTPKG)/lua/include
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/lua
+INCLUDES += -isystem$(RIOTPKG)/lua/include
 DIRS += $(RIOTPKG)/lua/contrib
diff --git a/pkg/lua/include/lua_run.h b/pkg/lua/include/lua_run.h
index 40376b8600..f898d6e9e8 100644
--- a/pkg/lua/include/lua_run.h
+++ b/pkg/lua/include/lua_run.h
@@ -182,14 +182,14 @@ LUALIB_API int lua_riot_openlibs(lua_State *L, uint16_t modmask);
  * or to manually reset the heap (only if there's no other thread using it).
  *
  * @param       modname     name of the module.
- * @param       memory      @see lua_riot_newstate()
- * @param       mem_size    @see lua_riot_newstate()
- * @param       modmask     @see lua_riot_newstate()
+ * @param       memory      See @ref lua_riot_newstate()
+ * @param       mem_size    See @ref lua_riot_newstate()
+ * @param       modmask     See @ref lua_riot_newstate()
  * @param[out]  retval      Value returned by the lua code, if it is a number,
  *                          or zero if no value is returned or the value is not
  *                          a number. If retval is null, the value is not stored.
  *
- * @return      An error code ( @see LUAR_ERRORS). LUAR_EXIT indicates no error.
+ * @return      An error code ( See @ref LUAR_ERRORS). LUAR_EXIT indicates no error.
  */
 LUALIB_API int lua_riot_do_module(const char *modname, void *memory, size_t mem_size,
                                   uint16_t modmask, int *retval);
@@ -200,16 +200,16 @@ LUALIB_API int lua_riot_do_module(const char *modname, void *memory, size_t mem_
  * Only text data (i.e. lua source code) can be loaded by this function. The
  * lua interpreter is not robust against corrupt binary code.
  *
- * @see lua_riot_do_module() for more information on internal errors.
+ * See @ref lua_riot_do_module() for more information on internal errors.
  *
  * @param       buf     Text data (lua source code).
  * @param       buflen  Size of the text data in bytes. If buf is
  *                      a zero-terminated string, the zero must not be counted.
- * @param       memory      @see lua_riot_newstate()
- * @param       mem_size    @see lua_riot_newstate()
- * @param       modmask     @see lua_riot_newstate()
- * @param[out]  retval      @see lua_riot_do_module()
- * @return      @see lua_riot_do_module().
+ * @param       memory      See @ref lua_riot_newstate()
+ * @param       mem_size    See @ref lua_riot_newstate()
+ * @param       modmask     See @ref lua_riot_newstate()
+ * @param[out]  retval      See @ref lua_riot_do_module()
+ * @return      See @ref lua_riot_do_module().
  */
 LUALIB_API int lua_riot_do_buffer(const uint8_t *buf, size_t buflen, void *memory,
                                   size_t mem_size, uint16_t modmask, int *retval);
diff --git a/pkg/lv_drivers/Makefile.include b/pkg/lv_drivers/Makefile.include
index 1f192e2d21..9047bfe855 100644
--- a/pkg/lv_drivers/Makefile.include
+++ b/pkg/lv_drivers/Makefile.include
@@ -1,5 +1,6 @@
-INCLUDES += -I$(PKGDIRBASE)/lv_drivers \
-            -I$(RIOTBASE)/pkg/lv_drivers/include \
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/lv_drivers \
+            -isystem$(RIOTBASE)/pkg/lv_drivers/include \
             #
 
 # Don't use relative includes in lv_drivers, already set in LVGL package
diff --git a/pkg/lvgl/Makefile.include b/pkg/lvgl/Makefile.include
index f900ae4af1..5bbacbda94 100644
--- a/pkg/lvgl/Makefile.include
+++ b/pkg/lvgl/Makefile.include
@@ -1,5 +1,6 @@
-INCLUDES += -I$(RIOTBASE)/pkg/lvgl/include
-INCLUDES += -I$(PKGDIRBASE)
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(RIOTBASE)/pkg/lvgl/include
+INCLUDES += -isystem$(PKGDIRBASE)
 
 # Don't use relative includes in lvgl
 CFLAGS += -DLV_CONF_INCLUDE_SIMPLE
diff --git a/pkg/mynewt-core/Makefile.include b/pkg/mynewt-core/Makefile.include
index 6a5cfa3145..f60eb9a419 100644
--- a/pkg/mynewt-core/Makefile.include
+++ b/pkg/mynewt-core/Makefile.include
@@ -1,8 +1,9 @@
-INCLUDES += -I$(RIOTPKG)/mynewt-core/include \
-            -I$(PKGDIRBASE)/mynewt-core/kernel/os/include \
-            -I$(PKGDIRBASE)/mynewt-core/hw/hal/include \
-            -I$(PKGDIRBASE)/mynewt-core/util/mem/include \
-            -I$(PKGDIRBASE)/mynewt-core/sys/stats/stub/include \
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(RIOTPKG)/mynewt-core/include \
+            -isystem$(PKGDIRBASE)/mynewt-core/kernel/os/include \
+            -isystem$(PKGDIRBASE)/mynewt-core/hw/hal/include \
+            -isystem$(PKGDIRBASE)/mynewt-core/util/mem/include \
+            -isystem$(PKGDIRBASE)/mynewt-core/sys/stats/stub/include \
             #
 
 DIRS += $(RIOTPKG)/mynewt-core/contrib \
diff --git a/pkg/nimble/Makefile.include b/pkg/nimble/Makefile.include
index ed2efc569d..9579939d79 100644
--- a/pkg/nimble/Makefile.include
+++ b/pkg/nimble/Makefile.include
@@ -1,7 +1,8 @@
-NIMIBASE = -I$(PKGDIRBASE)/nimble
+# Using -isystem instead of -I to prevent warnings for the following headers
+NIMIBASE = -isystem$(PKGDIRBASE)/nimble
 
 # include RIOT glue code headers
-INCLUDES += -I$(RIOTPKG)/nimble/contrib/include
+INCLUDES += -isystem$(RIOTPKG)/nimble/contrib/include
 
 # include generic nimble headers
 INCLUDES += $(NIMIBASE)/nimble/include
@@ -11,7 +12,7 @@ ifneq (,$(filter nimble_npl_riot,$(USEMODULE)))
   INCLUDES += $(NIMIBASE)/porting/npl/riot/include
 else
   INCLUDES += $(NIMIBASE)/porting/npl/riot/include/npl_syscfg
-  INCLUDES += -I$(RIOTPKG)/nimble/npl/include
+  INCLUDES += -isystem$(RIOTPKG)/nimble/npl/include
 endif
 INCLUDES += $(NIMIBASE)/porting/nimble/include
 
@@ -85,16 +86,16 @@ endif
 
 # include additional headers for RIOT specific NimBLE submodules
 ifneq (,$(filter nimble_addr,$(USEMODULE)))
-  INCLUDES += -I$(RIOTPKG)/nimble/addr/include
+  INCLUDES += -isystem$(RIOTPKG)/nimble/addr/include
 endif
 
 ifneq (,$(filter nimble_autoadv,$(USEMODULE)))
-  INCLUDES += -I$(RIOTPKG)/nimble/autoadv/include
+  INCLUDES += -isystem$(RIOTPKG)/nimble/autoadv/include
   DIRS += $(RIOTPKG)/nimble/autoadv
 endif
 
 ifneq (,$(filter nimble_autoconn,$(USEMODULE)))
-  INCLUDES += -I$(RIOTPKG)/nimble/autoconn/include
+  INCLUDES += -isystem$(RIOTPKG)/nimble/autoconn/include
 endif
 
 ifneq (,$(filter nimble_adv_ext,$(USEMODULE)))
@@ -124,7 +125,7 @@ else
 endif
 
 ifneq (,$(filter nimble_netif,$(USEMODULE)))
-  INCLUDES += -I$(RIOTPKG)/nimble/netif/include
+  INCLUDES += -isystem$(RIOTPKG)/nimble/netif/include
 
   # configure NimBLE's internals
   NIMBLE_MAX_CONN ?= 3
@@ -166,17 +167,17 @@ else
 endif
 
 ifneq (,$(filter nimble_rpble,$(USEMODULE)))
-  INCLUDES += -I$(RIOTPKG)/nimble/rpble/include
+  INCLUDES += -isystem$(RIOTPKG)/nimble/rpble/include
 endif
 
 ifneq (,$(filter nimble_scanlist,$(USEMODULE)))
-  INCLUDES += -I$(RIOTPKG)/nimble/scanlist/include
+  INCLUDES += -isystem$(RIOTPKG)/nimble/scanlist/include
 endif
 
 ifneq (,$(filter nimble_scanner,$(USEMODULE)))
-  INCLUDES += -I$(RIOTPKG)/nimble/scanner/include
+  INCLUDES += -isystem$(RIOTPKG)/nimble/scanner/include
 endif
 
 ifneq (,$(filter nimble_statconn,$(USEMODULE)))
-  INCLUDES += -I$(RIOTPKG)/nimble/statconn/include
+  INCLUDES += -isystem$(RIOTPKG)/nimble/statconn/include
 endif
diff --git a/pkg/opendsme/Makefile.include b/pkg/opendsme/Makefile.include
index ee5671f31a..8414228c8f 100644
--- a/pkg/opendsme/Makefile.include
+++ b/pkg/opendsme/Makefile.include
@@ -1,4 +1,5 @@
-INCLUDES += -I$(PKGDIRBASE)/opendsme
-INCLUDES += -I$(RIOTBASE)/pkg/opendsme/include
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/opendsme
+INCLUDES += -isystem$(RIOTBASE)/pkg/opendsme/include
 
 DIRS += $(RIOTBASE)/pkg/opendsme/contrib
diff --git a/pkg/openwsn/Makefile.include b/pkg/openwsn/Makefile.include
index 24be1a5db1..d26c2da122 100644
--- a/pkg/openwsn/Makefile.include
+++ b/pkg/openwsn/Makefile.include
@@ -15,32 +15,33 @@ PSEUDOMODULES += openwsn_serial \
 
 DIRS += $(RIOTBASE)/pkg/openwsn/contrib
 
-INCLUDES += -I$(PKGDIRBASE)/openwsn \
-            -I$(PKGDIRBASE)/openwsn/kernel \
-            -I$(PKGDIRBASE)/openwsn/inc \
-            -I$(PKGDIRBASE)/openwsn/drivers/common \
-            -I$(PKGDIRBASE)/openwsn/drivers/common/crypto \
-            -I$(PKGDIRBASE)/openwsn/bsp/boards/ \
-            -I$(PKGDIRBASE)/openwsn/openstack/ \
-            -I$(PKGDIRBASE)/openwsn/openstack/02a-MAClow \
-            -I$(PKGDIRBASE)/openwsn/openstack/02b-MAChigh \
-            -I$(PKGDIRBASE)/openwsn/openstack/03a-IPHC \
-            -I$(PKGDIRBASE)/openwsn/openstack/03b-IPv6 \
-            -I$(PKGDIRBASE)/openwsn/openstack/04-TRAN \
-            -I$(PKGDIRBASE)/openwsn/openstack/cross-layers \
-            -I$(PKGDIRBASE)/openwsn/openapps \
-            -I$(PKGDIRBASE)/openwsn/openapps/cjoin \
-            -I$(PKGDIRBASE)/openwsn/openweb \
-            -I$(PKGDIRBASE)/openwsn/openweb/opencoap \
-            -I$(RIOTBASE)/pkg/openwsn/include \
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/openwsn \
+            -isystem$(PKGDIRBASE)/openwsn/kernel \
+            -isystem$(PKGDIRBASE)/openwsn/inc \
+            -isystem$(PKGDIRBASE)/openwsn/drivers/common \
+            -isystem$(PKGDIRBASE)/openwsn/drivers/common/crypto \
+            -isystem$(PKGDIRBASE)/openwsn/bsp/boards/ \
+            -isystem$(PKGDIRBASE)/openwsn/openstack/ \
+            -isystem$(PKGDIRBASE)/openwsn/openstack/02a-MAClow \
+            -isystem$(PKGDIRBASE)/openwsn/openstack/02b-MAChigh \
+            -isystem$(PKGDIRBASE)/openwsn/openstack/03a-IPHC \
+            -isystem$(PKGDIRBASE)/openwsn/openstack/03b-IPv6 \
+            -isystem$(PKGDIRBASE)/openwsn/openstack/04-TRAN \
+            -isystem$(PKGDIRBASE)/openwsn/openstack/cross-layers \
+            -isystem$(PKGDIRBASE)/openwsn/openapps \
+            -isystem$(PKGDIRBASE)/openwsn/openapps/cjoin \
+            -isystem$(PKGDIRBASE)/openwsn/openweb \
+            -isystem$(PKGDIRBASE)/openwsn/openweb/opencoap \
+            -isystem$(RIOTBASE)/pkg/openwsn/include \
 
 ifneq (,$(filter openwsn_riotos,$(USEMODULE)))
-  INCLUDES += -I$(RIOTBASE)/pkg/openwsn/scheduler
+  INCLUDES += -isystem$(RIOTBASE)/pkg/openwsn/scheduler
   DIRS += $(RIOTBASE)/pkg/openwsn/scheduler
 endif
 
 ifneq (,$(filter openwsn_sock_udp,$(USEMODULE)))
-  INCLUDES += -I$(RIOTBASE)/pkg/openwsn/sock
+  INCLUDES += -isystem$(RIOTBASE)/pkg/openwsn/sock
   DIRS += $(RIOTBASE)/pkg/openwsn/sock
 endif
 
diff --git a/pkg/paho-mqtt/Makefile.include b/pkg/paho-mqtt/Makefile.include
index cdcf5597c8..1a9b65f0fc 100644
--- a/pkg/paho-mqtt/Makefile.include
+++ b/pkg/paho-mqtt/Makefile.include
@@ -1,6 +1,7 @@
-INCLUDES += -I$(PKGDIRBASE)/paho-mqtt/MQTTClient-C/src/
-INCLUDES += -I$(PKGDIRBASE)/paho-mqtt/MQTTPacket/src
-INCLUDES += -I$(RIOTBASE)/pkg/paho-mqtt/include
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/paho-mqtt/MQTTClient-C/src/
+INCLUDES += -isystem$(PKGDIRBASE)/paho-mqtt/MQTTPacket/src
+INCLUDES += -isystem$(RIOTBASE)/pkg/paho-mqtt/include
 
 DIRS += $(RIOTBASE)/pkg/paho-mqtt/contrib
 
diff --git a/pkg/relic/Makefile.include b/pkg/relic/Makefile.include
index f94915aee0..e7d48ead02 100644
--- a/pkg/relic/Makefile.include
+++ b/pkg/relic/Makefile.include
@@ -1,3 +1,4 @@
-INCLUDES += -I$(PKGDIRBASE)/relic/include
-INCLUDES += -I$(BINDIR)/pkg-build/relic/include
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/relic/include
+INCLUDES += -isystem$(BINDIR)/pkg-build/relic/include
 ARCHIVES += $(BINDIR)/relic.a
diff --git a/pkg/semtech-loramac/Makefile b/pkg/semtech-loramac/Makefile
index 111e607274..5a80c99fbe 100644
--- a/pkg/semtech-loramac/Makefile
+++ b/pkg/semtech-loramac/Makefile
@@ -5,10 +5,11 @@ PKG_LICENSE=BSD-3-Clause
 
 include $(RIOTBASE)/pkg/pkg.mk
 
-INCLUDES += -I$(PKGDIRBASE)/semtech-loramac/src/mac \
-            -I$(PKGDIRBASE)/semtech-loramac/src/boards/mcu \
-            -I$(PKGDIRBASE)/semtech-loramac/src/system/crypto \
-            -I$(PKGDIRBASE)/semtech-loramac/src
+# Use -isystem instead of -I to disable warnings for these headers
+INCLUDES += -isystem$(PKGDIRBASE)/semtech-loramac/src/mac \
+            -isystem$(PKGDIRBASE)/semtech-loramac/src/boards/mcu \
+            -isystem$(PKGDIRBASE)/semtech-loramac/src/system/crypto \
+            -isystem$(PKGDIRBASE)/semtech-loramac/src
 
 LORAMAC_MODULES = loramac_arch loramac_crypto loramac_mac loramac_region
 
diff --git a/pkg/semtech-loramac/Makefile.include b/pkg/semtech-loramac/Makefile.include
index 1ed77e70ec..3cb8b067b0 100644
--- a/pkg/semtech-loramac/Makefile.include
+++ b/pkg/semtech-loramac/Makefile.include
@@ -1,4 +1,5 @@
-INCLUDES += -I$(RIOTBASE)/pkg/semtech-loramac/include
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(RIOTBASE)/pkg/semtech-loramac/include
 
 DIRS += $(RIOTBASE)/pkg/semtech-loramac/contrib
 
diff --git a/pkg/semtech-loramac/contrib/Makefile b/pkg/semtech-loramac/contrib/Makefile
index baadd04b0b..d2e353da14 100644
--- a/pkg/semtech-loramac/contrib/Makefile
+++ b/pkg/semtech-loramac/contrib/Makefile
@@ -1,9 +1,10 @@
 MODULE := semtech_loramac_contrib
 
-INCLUDES += -I$(PKGDIRBASE)/semtech-loramac/src/mac \
-            -I$(PKGDIRBASE)/semtech-loramac/src/boards \
-            -I$(PKGDIRBASE)/semtech-loramac/src/radio \
-            -I$(PKGDIRBASE)/semtech-loramac/src/system/crypto \
-            -I$(PKGDIRBASE)/semtech-loramac/src
+# Use -isystem instead of -I to disable warnings about these headers
+INCLUDES += -isystem$(PKGDIRBASE)/semtech-loramac/src/mac \
+            -isystem$(PKGDIRBASE)/semtech-loramac/src/boards \
+            -isystem$(PKGDIRBASE)/semtech-loramac/src/radio \
+            -isystem$(PKGDIRBASE)/semtech-loramac/src/system/crypto \
+            -isystem$(PKGDIRBASE)/semtech-loramac/src
 
 include $(RIOTBASE)/Makefile.base
diff --git a/pkg/tinycrypt/Makefile.include b/pkg/tinycrypt/Makefile.include
index ac7a28bc30..2899d47cee 100644
--- a/pkg/tinycrypt/Makefile.include
+++ b/pkg/tinycrypt/Makefile.include
@@ -1 +1,2 @@
-INCLUDES += -I$(PKGDIRBASE)/tinycrypt/lib/include
+# Using -isyste instead of -I to avoid warnings about these headers
+INCLUDES += -isystem$(PKGDIRBASE)/tinycrypt/lib/include
diff --git a/pkg/tinydtls/Makefile.include b/pkg/tinydtls/Makefile.include
index 9d4add6ccf..2db314b02f 100644
--- a/pkg/tinydtls/Makefile.include
+++ b/pkg/tinydtls/Makefile.include
@@ -1,13 +1,14 @@
 PKG_BUILDDIR ?= $(PKGDIRBASE)/tinydtls
 
-INCLUDES += -I$(PKG_BUILDDIR)
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKG_BUILDDIR)
 
 ifeq ($(TOOLCHAIN), llvm)
   CFLAGS += -Wno-gnu-zero-variadic-macro-arguments -Wno-unused-function
 endif
 
-INCLUDES += -I$(RIOTBASE)/pkg/tinydtls/include
-INCLUDES += -I$(PKG_BUILDDIR)
+INCLUDES += -isystem$(RIOTBASE)/pkg/tinydtls/include
+INCLUDES += -isystem$(PKG_BUILDDIR)
 # Mandatory for tinyDTLS
 CFLAGS += -DDTLSv12 -DWITH_SHA256
 
diff --git a/pkg/umorse/Makefile.include b/pkg/umorse/Makefile.include
index f3fc9946a6..3b806ca8b9 100644
--- a/pkg/umorse/Makefile.include
+++ b/pkg/umorse/Makefile.include
@@ -1 +1,2 @@
-INCLUDES += -I$(PKGDIRBASE)/umorse
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/umorse
diff --git a/pkg/uwb-core/Makefile.include b/pkg/uwb-core/Makefile.include
index 1a03d51b5b..7a166f7787 100644
--- a/pkg/uwb-core/Makefile.include
+++ b/pkg/uwb-core/Makefile.include
@@ -1,17 +1,18 @@
-INCLUDES += -I$(PKGDIRBASE)/uwb-core/hw/drivers/uwb/include/ \
-            -I$(PKGDIRBASE)/uwb-core/lib/euclid/include \
-            -I$(PKGDIRBASE)/uwb-core/lib/dsp/include \
-            -I$(PKGDIRBASE)/uwb-core/lib/json/include \
-            -I$(PKGDIRBASE)/uwb-core/lib/rng_math/include \
-            -I$(PKGDIRBASE)/uwb-core/lib/twr_ss/include \
-            -I$(PKGDIRBASE)/uwb-core/lib/twr_ss_ext/include \
-            -I$(PKGDIRBASE)/uwb-core/lib/twr_ss_ack/include \
-            -I$(PKGDIRBASE)/uwb-core/lib/twr_ds/include \
-            -I$(PKGDIRBASE)/uwb-core/lib/twr_ds_ext/include \
-            -I$(PKGDIRBASE)/uwb-core/lib/uwb_rng/include \
-            -I$(PKGDIRBASE)/uwb-core/porting/dpl/riot/include/ \
-            -I$(PKGDIRBASE)/uwb-core/sys/uwbcfg/include \
-            -I$(RIOTPKG)/uwb-core/include \
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(PKGDIRBASE)/uwb-core/hw/drivers/uwb/include/ \
+            -isystem$(PKGDIRBASE)/uwb-core/lib/euclid/include \
+            -isystem$(PKGDIRBASE)/uwb-core/lib/dsp/include \
+            -isystem$(PKGDIRBASE)/uwb-core/lib/json/include \
+            -isystem$(PKGDIRBASE)/uwb-core/lib/rng_math/include \
+            -isystem$(PKGDIRBASE)/uwb-core/lib/twr_ss/include \
+            -isystem$(PKGDIRBASE)/uwb-core/lib/twr_ss_ext/include \
+            -isystem$(PKGDIRBASE)/uwb-core/lib/twr_ss_ack/include \
+            -isystem$(PKGDIRBASE)/uwb-core/lib/twr_ds/include \
+            -isystem$(PKGDIRBASE)/uwb-core/lib/twr_ds_ext/include \
+            -isystem$(PKGDIRBASE)/uwb-core/lib/uwb_rng/include \
+            -isystem$(PKGDIRBASE)/uwb-core/porting/dpl/riot/include/ \
+            -isystem$(PKGDIRBASE)/uwb-core/sys/uwbcfg/include \
+            -isystem$(RIOTPKG)/uwb-core/include \
             #
 
 PSEUDOMODULES += uwb-core_dpl
diff --git a/pkg/wakaama/Makefile.include b/pkg/wakaama/Makefile.include
index 69ca42848e..8ace74b629 100644
--- a/pkg/wakaama/Makefile.include
+++ b/pkg/wakaama/Makefile.include
@@ -1,10 +1,11 @@
 DIRS += $(RIOTBASE)/pkg/wakaama/contrib
 
-INCLUDES += -I$(RIOTBASE)/pkg/wakaama/include
-INCLUDES += -I$(PKGDIRBASE)/wakaama/include
-INCLUDES += -I$(PKGDIRBASE)/wakaama/core
-INCLUDES += -I$(PKGDIRBASE)/wakaama/data
-INCLUDES += -I$(PKGDIRBASE)/wakaama/coap/er-coap-13
+# Using -isystem instead of -I to prevent warnings for the following headers
+INCLUDES += -isystem$(RIOTBASE)/pkg/wakaama/include
+INCLUDES += -isystem$(PKGDIRBASE)/wakaama/include
+INCLUDES += -isystem$(PKGDIRBASE)/wakaama/core
+INCLUDES += -isystem$(PKGDIRBASE)/wakaama/data
+INCLUDES += -isystem$(PKGDIRBASE)/wakaama/coap/er-coap-13
 
 # NOTE: Use wakaama in client mode
 CFLAGS += -DLWM2M_CLIENT_MODE