--- SCP/makefile.orig	2020-08-23 21:58:56 UTC
+++ SCP/makefile
@@ -532,10 +532,12 @@ ifneq ($(DONT_USE_READER_THREAD),)
 endif
 
 
-# Shut up annoying clang default warnings.
+# Shut up annoying clang default warnings, and also fix
+# multiply defined symbols on clang 11 and above
 
-ifeq ($(GCC),clang)
+ifeq ($(findstring clang,$(COMPILER_NAME)),clang)
   OS_CCDEFS += -Wno-parentheses -Wno-bitwise-op-parentheses -Wno-dangling-else
+  CFLAGS_O += -fcommon
 endif