diff --git a/lib/modules/manager/pep621/processors/pdm.ts b/lib/modules/manager/pep621/processors/pdm.ts
index 98afea80563e5c6d7fb9c4ea2874ddea14310ed8..f1222f9bd315a56ce88a95a7450889071568d1c8 100644
--- a/lib/modules/manager/pep621/processors/pdm.ts
+++ b/lib/modules/manager/pep621/processors/pdm.ts
@@ -48,7 +48,7 @@ export class PdmProcessor implements PyProjectProcessor {
       registryUrls.push(source.url);
     }
     for (const dep of deps) {
-      dep.registryUrls = registryUrls;
+      dep.registryUrls = [...registryUrls];
     }
 
     return deps;