diff --git a/Makefile b/Makefile
index 5870d423..542fee06 100755
--- a/Makefile
+++ b/Makefile
@@ -44,9 +44,11 @@ endif
 # Set tools
 
 # Use clang if it's available.
+ifeq ($(origin CC),default)
 ifneq (, $(shell which clang))
 CC := clang
 endif
+endif
 
 ifeq ($(PLATFORM),windows32)
 # To force use of the Unix version instead of the Windows version