diff --git a/boards/Makefile.include.cortexm_common b/boards/Makefile.include.cortexm_common
index e94090fa30330c45ee5c4ad78fb0f322897455a8..93073ff6b9a26850061163008d65a04f1edb7de5 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