2 files changed, 2 insertions, 2 deletions
diff --git a/pkgs/applications/graphics/gimp/default.nix b/pkgs/applications/graphics/gimp/default.nix
index 73429a5ad37bd..8ffc0a0424e5b 100644
--- a/pkgs/applications/graphics/gimp/default.nix
+++ b/pkgs/applications/graphics/gimp/default.nix
@@ -154,7 +154,7 @@ in stdenv.mkDerivation rec {
 
   doCheck = true;
 
-  env.NIX_CFLAGS_COMPILE = lib.optional stdenv.isDarwin "-DGDK_OSX_BIG_SUR=16";
+  env.NIX_CFLAGS_COMPILE = lib.optionalString stdenv.isDarwin "-DGDK_OSX_BIG_SUR=16";
 
   # Check if librsvg was built with --disable-pixbuf-loader.
   PKG_CONFIG_GDK_PIXBUF_2_0_GDK_PIXBUF_MODULEDIR = "${librsvg}/${gdk-pixbuf.moduleDir}";
diff --git a/pkgs/applications/graphics/gnuclad/default.nix b/pkgs/applications/graphics/gnuclad/default.nix
index a2eb640bc1f13..b90735d850837 100644
--- a/pkgs/applications/graphics/gnuclad/default.nix
+++ b/pkgs/applications/graphics/gnuclad/default.nix
@@ -10,7 +10,7 @@ stdenv.mkDerivation rec {
     sha256 = "0ka2kscpjff7gflsargv3r9fdaxhkf3nym9mfaln3pnq6q7fwdki";
   };
 
-  env.NIX_CFLAGS_COMPILE = lib.optional stdenv.cc.isGNU "-Wno-error=catch-value";
+  env.NIX_CFLAGS_COMPILE = lib.optionalString stdenv.cc.isGNU "-Wno-error=catch-value";
 
   nativeBuildInputs = [ pkg-config ];