diff --git a/internal/db/runtime-store.test.ts b/internal/db/runtime-store.test.ts
index de9867d5..7160a84a 100644
--- a/internal/db/runtime-store.test.ts
+++ b/internal/db/runtime-store.test.ts
@@ -154,6 +154,7 @@ test("postgres pool config makes HWLAB_CLOUD_DB_SSL_MODE authoritative over URL
 
   assert.deepEqual(required.ssl, { rejectUnauthorized: false });
   assert.equal(new URL(required.connectionString).searchParams.get("sslmode"), "require");
+  assert.equal(new URL(required.connectionString).searchParams.get("uselibpqcompat"), "true");
 });
 
 test("configured postgres runtime passes normalized pool config to pg", async () => {
diff --git a/internal/db/runtime-store.ts b/internal/db/runtime-store.ts
index e5f180c4..cc2af0b3 100644
--- a/internal/db/runtime-store.ts
+++ b/internal/db/runtime-store.ts
@@ -1356,6 +1356,7 @@ function normalizePostgresConnectionStringForSslMode(dbUrl, sslMode) {
   }
   if (sslMode !== "disable") {
     url.searchParams.set("sslmode", "require");
+    url.searchParams.set("uselibpqcompat", "true");
   }
   return url.toString();
 }