diff --git a/.gitignore b/.gitignore
index 2831abe..61aba11 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,6 +13,10 @@ src/version.js
 Makefile
 package.json
 
+# generated by Makefile
+src/.gitignore
+test/.gitignore
+
 # generated by gen-index
 src/**/index.js
 
diff --git a/Makefile.am b/Makefile.am
index d1a2b1c..d608717 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -39,13 +39,18 @@ dist-hook: check
 
 # used to force typescript compilation (it handles its own incremental
 # compilation and dependency discovery)
-$(tsout): FORCE
+$(tsout): FORCE $(path_src)/.gitignore $(path_test)/.gitignore
 	node_modules/.bin/tsc
 
 modindex: $(nsindex)
 %/index.js: FORCE $(tsout)
 	./tools/gen-index "$*" > "$@"
 
+# ignore compiled JS files (this can be removed once all files are TS)
+%/.gitignore: FORCE
+	@echo "# THIS FILE IS GENERATED; DO NOT MODIFY!" > $@
+	( cd $*/ && find . -name '*.ts' -printf "%P\n" | sed 's/\.ts$$/.js/' ) >> $@
+
 test: check
 check: $(tsout)
 	PATH="$(PATH):$(CURDIR)/node_modules/mocha/bin" \