diff --git a/pkgs/build-support/fetchcvs/builder.sh b/pkgs/build-support/fetchcvs/builder.sh
index 0975c3478820..fe1019aafc2f 100644
--- a/pkgs/build-support/fetchcvs/builder.sh
+++ b/pkgs/build-support/fetchcvs/builder.sh
@@ -1,6 +1,6 @@
 source $stdenv/setup
 
-(echo '#!/usr/bin/env sh'; \
+(echo "#!$SHELL"; \
  echo 'ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no "$@"') > ssh
 chmod +x ssh
 export CVS_RSH=$PWD/ssh