--- a/Makefile
+++ b/Makefile
@@ -3,17 +3,19 @@
 PREFIX ?= /usr/local
 SHARD_BIN ?= ../../bin
 
+.PHONY: build
 build: bin/ameba
+
 bin/ameba:
 	$(SHARDS_BIN) build $(CRFLAGS)
 clean:
 	rm -f ./bin/ameba ./bin/ameba.dwarf
-install: build
+install: bin/ameba
 	mkdir -p $(PREFIX)/bin
 	cp ./bin/ameba $(PREFIX)/bin
-bin: build
+bin: bin/ameba
 	mkdir -p $(SHARD_BIN)
 	cp ./bin/ameba $(SHARD_BIN)
-test: build
-	$(CRYSTAL_BIN) spec
+test: bin/ameba
+	$(CRYSTAL_BIN) spec $(SPEC_FLAGS)
 	./bin/ameba --all