--- a/Makefile
+++ b/Makefile
@@ -35,6 +35,9 @@ FZJAVA = $(BUILD_DIR)/bin/fzjava
 CLASSES_DIR = $(BUILD_DIR)/classes
 CLASSES_DIR_LOGO = $(BUILD_DIR)/classes_logo
 FUZION_BIN_SH = /bin/sh
+CC :=
+CFLAGS :=
+LDFLAGS :=
 
 ifeq ($(FUZION_DEBUG_SYMBOLS),true)
 	JAVAC += -g
@@ -1438,11 +1441,12 @@ ifeq ($(OS),Windows_NT)
 	-lMswsock -lAdvApi32 -lWs2_32
 	touch $(FUZION_RT)
 else
-	clang -Wall -Werror -O3 -shared -fPIC \
+	$(CC) -Wall -Werror -shared -fPIC \
 	-DFUZION_ENABLE_THREADS \
-	-fno-trigraphs -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -std=c11 \
+	-fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -std=c11 \
+	$(CFLAGS) $(LDFLAGS) \
 	$(BUILD_DIR)/include/posix.c $(BUILD_DIR)/include/shared.c -o $(BUILD_DIR)/lib/libfuzion.so
-	cp $(BUILD_DIR)/lib/libfuzion.so $(BUILD_DIR)/lib/libfuzion.dylib
+#	cp $(BUILD_DIR)/lib/libfuzion.so $(BUILD_DIR)/lib/libfuzion.dylib
 	touch $(FUZION_RT)
 endif
 # NYI: eventuall link libgc