From d60532bc7197424cc57606c207ce2b6749bcd34e Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Mon, 25 Nov 2019 14:20:10 +0000
Subject: [PATCH] coq: Fix setup hook

---
 pkgs/applications/science/logic/coq/default.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pkgs/applications/science/logic/coq/default.nix b/pkgs/applications/science/logic/coq/default.nix
index a463a2c5f3a..bf2d0396f69 100644
--- a/pkgs/applications/science/logic/coq/default.nix
+++ b/pkgs/applications/science/logic/coq/default.nix
@@ -124,7 +124,7 @@ self = stdenv.mkDerivation {
   setupHook = writeText "setupHook.sh" ''
     addCoqPath () {
       if test -d "''$1/lib/coq/${coq-version}/user-contrib"; then
-        export COQPATH="''${COQPATH}''${COQPATH:+:}''$1/lib/coq/${coq-version}/user-contrib/"
+        export COQPATH="''${COQPATH-}''${COQPATH:+:}''$1/lib/coq/${coq-version}/user-contrib/"
       fi
     }