diff --git a/makefile_include.mk b/makefile_include.mk
index 3cf9069..0f1baa7 100644
--- a/makefile_include.mk
+++ b/makefile_include.mk
@@ -343,8 +343,8 @@ src/hashes/sha2/sha512_224.o: src/hashes/sha2/sha512.c src/hashes/sha2/sha512_22
 src/hashes/sha2/sha512_256.o: src/hashes/sha2/sha512.c src/hashes/sha2/sha512_256.c
 src/hashes/sha2/sha256.o: src/hashes/sha2/sha256.c src/hashes/sha2/sha224.c
 
-$(DOBJECTS): LTC_CFLAGS += -Itests
-$(TOBJECTS): LTC_CFLAGS += -Itests
+$(DOBJECTS): LTC_CFLAGS := -Itests $(LTC_CFLAGS)
+$(TOBJECTS): LTC_CFLAGS := -Itests $(LTC_CFLAGS)
 
 #This rule makes the libtomcrypt library.
 library: $(LIBNAME)