diff --git a/Makefile b/Makefile
index 2c428de..9cf3303 100644
--- a/Makefile
+++ b/Makefile
@@ -15,7 +15,7 @@ CLS := $(SRCS:$(SRC_DIR)/%.java=$(OUT_DIR)/%.class)
 
 .PHONY: all clean
 
-all: $(CLS)
+all: pack
 
 $(CLS): $(OUT_DIR)/%.class: $(SRC_DIR)/%.java
 	mkdir -p build
@@ -25,7 +25,7 @@ clean:
 	rm -rf build/
 	rm -f result.jar
 
-pack:
+pack result.jar: $(CLS)
 	jar -cmf META-INF/MANIFEST.MF result.jar -C build . -C res .
 
 run: