diff --git a/makefile_web b/makefile_web
index 58f7f1f5..4a4744c8 100644
--- a/makefile_web
+++ b/makefile_web
@@ -1,3 +1,6 @@
+SRC_DIR = ./src
+SRCS := $(wildcard $(SRC_DIR)/**)
+
 .PHONY: clean full-clean web tarball
 
 web: out/boids.js out/boids.wasm out/index.html
@@ -7,7 +10,7 @@ tarball: boids_web_root.tar
 boids_web_root.tar: out/boids.js out/boids.wasm out/index.html
 	tar -caf $@ $<
 
-target/wasm32-unknown-unknown/wasm-release/another-boids-in-rust.wasm:
+target/wasm32-unknown-unknown/wasm-release/another-boids-in-rust.wasm: $(SRCS)
 	cargo build --profile wasm-release --target wasm32-unknown-unknown
 
 out: