diff --git a/boards/Makefile.include.cortexm_common b/boards/Makefile.include.cortexm_common
index 120798937577e2878bbb19f143748f7f5c15e114..5d922dba1a245c2000c30a6a939ad499564e20fa 100644
--- a/boards/Makefile.include.cortexm_common
+++ b/boards/Makefile.include.cortexm_common
@@ -11,6 +11,12 @@ ifeq (clang,$(TOOLCHAIN))
 # opposed to one set in the environment)
 override TOOLCHAIN := llvm
 endif
+# TOOLCHAIN = gcc is an alias for TOOLCHAIN = gnu
+ifeq (gcc,$(TOOLCHAIN))
+# use override so that we can redefine a variable set on the command line (as
+# opposed to one set in the environment)
+override TOOLCHAIN := gnu
+endif
 
 export TOOLCHAIN