diff --git a/lib/rb/Makefile.am b/lib/rb/Makefile.am
index 2d0c12e..658eb7d 100755
--- a/lib/rb/Makefile.am
+++ b/lib/rb/Makefile.am
@@ -23,7 +23,7 @@
 
 all-local:
 	$(BUNDLER) install
-	$(BUNDLER) exec rake
+	$(BUNDLER) exec rake build_ext
 
 install-exec-hook:
 	$(BUNDLER) exec rake install