diff --git a/Makefile b/Makefile
index bcfdda4..1eeef96 100644
--- a/Makefile
+++ b/Makefile
@@ -14,7 +14,7 @@ all: clean build
 
 build: $(MIN_PATH)
 
-$(HAXE_PATH): $(shell find src -name '*.hx')
+$(HAXE_PATH): $(shell find src -name '*.hx') $(POLYFILL_SRC)
 	haxe build.hxml $(HAXE_FLAGS)
 
 $(MIN_PATH): $(POLYFILL_PATH)