diff --git a/pkgs/build-support/test-equal-derivation.nix b/pkgs/build-support/test-equal-derivation.nix
index 5d2185ce1652..652f3716b2a7 100644
--- a/pkgs/build-support/test-equal-derivation.nix
+++ b/pkgs/build-support/test-equal-derivation.nix
@@ -23,7 +23,7 @@ let
   drvB = builtins.unsafeDiscardOutputDependency b.drvPath or (throw "testEqualDerivation third argument must be a package");
   name =
     if a?name
-    then lib.strings.sanitizeDerivationName "testEqualDerivation-${a.name}"
+    then "testEqualDerivation-${a.name}"
     else "testEqualDerivation";
 in
 if drvA == drvB then