diff --git a/cpu/atxmega/include/periph_cpu.h b/cpu/atxmega/include/periph_cpu.h
index 8246847513..440f09266a 100644
--- a/cpu/atxmega/include/periph_cpu.h
+++ b/cpu/atxmega/include/periph_cpu.h
@@ -418,7 +418,7 @@ typedef enum {
 /* for compatibility between different versions of AVR libc: Legacy versions
  * occasionally use ASPACE instead of ASIZE for some MCUs, while new AVR libc
  * uses ASIZE as name consistently */
-#ifdef EBI_CS_ASPACE_gm
+#ifndef EBI_CS_ASIZE_gm
 typedef EBI_CS_ASPACE_t EBI_CS_ASIZE_t;
 #define EBI_CS_ASIZE_256B_gc EBI_CS_ASPACE_256B_gc
 #define EBI_CS_ASIZE_512B_gc EBI_CS_ASPACE_512B_gc
diff --git a/examples/micropython/Makefile b/examples/micropython/Makefile
index d735268cfb..339eda7289 100644
--- a/examples/micropython/Makefile
+++ b/examples/micropython/Makefile
@@ -31,4 +31,7 @@ FEATURES_OPTIONAL += periph_spi
 # a terminal is opened to synchronize.
 TESTRUNNER_RESET_AFTER_TERM ?= 1
 
+# failing on native with floating point exception (#15870)
+TEST_ON_CI_BLACKLIST = all
+
 include $(RIOTBASE)/Makefile.include
diff --git a/pkg/libhydrogen/Makefile b/pkg/libhydrogen/Makefile
index 84fd53327a..0c24e6ac9a 100644
--- a/pkg/libhydrogen/Makefile
+++ b/pkg/libhydrogen/Makefile
@@ -9,5 +9,8 @@ include $(RIOTBASE)/pkg/pkg.mk
 CFLAGS += -Wno-type-limits
 CFLAGS += -Wno-cast-align
 
+# Silence warning popping up since `gcc version 11.2.0 (Ubuntu 11.2.0-19ubuntu1)`
+CFLAGS += -Wno-stringop-overflow
+
 all:
 	$(QQ)"$(MAKE)" -C $(PKG_SOURCE_DIR) -f $(RIOTBASE)/Makefile.base
diff --git a/sys/shell/cmds/dfplayer.c b/sys/shell/cmds/dfplayer.c
index 486edb6868..ba8d559182 100644
--- a/sys/shell/cmds/dfplayer.c
+++ b/sys/shell/cmds/dfplayer.c
@@ -172,7 +172,7 @@ static void _print_equalizer(dfplayer_t *dev)
 
 static void _print_mode(dfplayer_t *dev)
 {
-    dfplayer_mode_t mode;
+    dfplayer_mode_t mode = {0};
     int retval = dfplayer_get_mode(dev, &mode);
     if (retval) {
         _print_error(retval);