diff --git a/pkgs/development/python-modules/ray/default.nix b/pkgs/development/python-modules/ray/default.nix
index 5a3c141bf44e..3041b01a1141 100644
--- a/pkgs/development/python-modules/ray/default.nix
+++ b/pkgs/development/python-modules/ray/default.nix
@@ -119,7 +119,9 @@ buildPythonPackage rec {
       python = pyShortVersion;
       abi = pyShortVersion;
       platform = platforms.${stdenv.hostPlatform.system} or { };
-      sha256 = hashes.${stdenv.hostPlatform.system}.${pyShortVersion} or { };
+      sha256 =
+        hashes.${stdenv.hostPlatform.system}.${pyShortVersion}
+          or (throw "No hash specified for '${stdenv.hostPlatform.system}.${pyShortVersion}'");
     };
 
   nativeBuildInputs = lib.optionals stdenv.hostPlatform.isLinux [