diff --git a/pkgs/stdenv/generic/check-meta.nix b/pkgs/stdenv/generic/check-meta.nix
index 7b06692ac8ce..ce39130d3151 100644
--- a/pkgs/stdenv/generic/check-meta.nix
+++ b/pkgs/stdenv/generic/check-meta.nix
@@ -16,8 +16,11 @@ let
   allowUnfree = config.allowUnfree
     || builtins.getEnv "NIXPKGS_ALLOW_UNFREE" == "1";
 
-  allowNonSource = config.allowNonSource or true
-    && builtins.getEnv "NIXPKGS_ALLOW_NONSOURCE" != "0";
+  allowNonSource = let
+    envVar = builtins.getEnv "NIXPKGS_ALLOW_NONSOURCE";
+  in if envVar != ""
+     then envVar != "0"
+     else config.allowNonSource or true;
 
   allowlist = config.allowlistedLicenses or config.whitelistedLicenses or [];
   blocklist = config.blocklistedLicenses or config.blacklistedLicenses or [];