diff --git a/pkgs/development/libraries/libgweather/default.nix b/pkgs/development/libraries/libgweather/default.nix
index 0ce3450f053e..53c4b5f259b7 100644
--- a/pkgs/development/libraries/libgweather/default.nix
+++ b/pkgs/development/libraries/libgweather/default.nix
@@ -65,6 +65,8 @@ stdenv.mkDerivation rec {
   mesonFlags = [
     "-Dzoneinfo_dir=${tzdata}/share/zoneinfo"
     (lib.mesonBool "introspection" withIntrospection)
+  ] ++ lib.optionals stdenv.isDarwin [
+    "-Dc_args=-D_DARWIN_C_SOURCE"
   ];
 
   postPatch = ''