diff --git a/Makefile b/Makefile
index c006ddc..f7edfb9 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@ prepare:
 	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 \
 	)
 
 .SILENT: