diff --git a/nixos/tests/installed-tests/libxmlb.nix b/nixos/tests/installed-tests/libxmlb.nix
index af2bbe9c35e2..f45b97e8341f 100644
--- a/nixos/tests/installed-tests/libxmlb.nix
+++ b/nixos/tests/installed-tests/libxmlb.nix
@@ -2,4 +2,10 @@
 
 makeInstalledTest {
   tested = pkgs.libxmlb;
+
+  testConfig = {
+    environment.variables = {
+      G_TEST_SRCDIR = "${pkgs.libxmlb.installedTests}/libexec/installed-tests/libxmlb";
+    };
+  };
 }