diff --git a/boards/native/Makefile.include b/boards/native/Makefile.include
index 9ee94c3eb3..5c0458ccc7 100644
--- a/boards/native/Makefile.include
+++ b/boards/native/Makefile.include
@@ -95,9 +95,9 @@ export LINKFLAGS += -ffunction-sections
 
 # set the tap interface for term/valgrind
 ifneq (,$(filter netdev_default gnrc_netdev_default,$(USEMODULE)))
-  export PORT ?= tap0
+  PORT ?= tap0
 else
-  export PORT =
+  PORT =
 endif
 
 TERMFLAGS := $(PORT) $(TERMFLAGS)
diff --git a/makefiles/tools/serial.inc.mk b/makefiles/tools/serial.inc.mk
index 8abcf7fe1d..115647d84f 100644
--- a/makefiles/tools/serial.inc.mk
+++ b/makefiles/tools/serial.inc.mk
@@ -8,7 +8,6 @@ endif
 ifeq ($(PORT),)
   $(info Warning: no PORT set!)
 endif
-export PORT
 
 export BAUD ?= 115200
 
diff --git a/makefiles/vars.inc.mk b/makefiles/vars.inc.mk
index b46d5f70b5..850476fbe6 100644
--- a/makefiles/vars.inc.mk
+++ b/makefiles/vars.inc.mk
@@ -74,7 +74,7 @@ export GIT_CACHE_DIR         # path to git-cache cache directory
 export FLASH_ADDR            # Define an offset to flash code into ROM memory.
 # TERMPROG                   # The command to call on "make term".
 # TERMFLAGS                  # Additional parameters to supply to TERMPROG.
-export PORT                  # The port to connect the TERMPROG to.
+# PORT                       # The port to connect the TERMPROG to.
 export ELFFILE               # The unstripped result of the compilation.
 export HEXFILE               # The stripped result of the compilation.
 # FLASHFILE                  # The output file used for flashing (transition phase: only if defined)