diff --git a/pkgs/stdenv/adapters.nix b/pkgs/stdenv/adapters.nix
index 54527f841242..34198cff65d9 100644
--- a/pkgs/stdenv/adapters.nix
+++ b/pkgs/stdenv/adapters.nix
@@ -198,7 +198,8 @@ rec {
             {
               env = prevAttrs.env // {
                 NIX_CFLAGS_LINK =
-                  toString args.env.NIX_CFLAGS_LINK + lib.optionalString (stdenv.cc.isGNU or false) " -static-libgcc";
+                  toString (args.env.NIX_CFLAGS_LINK or "")
+                  + lib.optionalString (stdenv.cc.isGNU or false) " -static-libgcc";
               };
             }
           else