diff --git a/Makefile b/Makefile
index e4608f5..e0f3755 100644
--- a/Makefile
+++ b/Makefile
@@ -10,14 +10,14 @@ prepare-assert.sh:
 	test -f "test/assert.sh" || ( \
 		echo "fetching assert.sh..." && \
 		curl -s -L -o test/assert.sh \
-			https://raw.github.com/lehmannro/assert.sh/master/assert.sh \
+			https://raw.github.com/lehmannro/assert.sh/v1.0.2/assert.sh \
 	)
 
 prepare-stub.sh:
 	test -f "test/stub.sh" || ( \
 		echo "fetching stub.sh..." && \
 		curl -s -L -o test/stub.sh \
-			https://raw.github.com/jimeh/stub.sh/master/stub.sh \
+			https://raw.github.com/jimeh/stub.sh/v0.2.0/stub.sh \
 	)
 
 .SILENT: