diff --git a/pkgs/build-support/fetchurl/builder.sh b/pkgs/build-support/fetchurl/builder.sh
index 6a4190f7592..ac925dbcbdb 100644
--- a/pkgs/build-support/fetchurl/builder.sh
+++ b/pkgs/build-support/fetchurl/builder.sh
@@ -2,7 +2,7 @@
 
 header "downloading $out from $url"
 
-curl "$url" > "$out"
+curl --fail "$url" > "$out"
 
 actual=$(md5sum -b "$out" | cut -c1-32)
 if test "$actual" != "$md5"; then