diff --git a/customdiff_test.go b/customdiff_test.go
index effe9d8..610bff0 100644
--- a/customdiff_test.go
+++ b/customdiff_test.go
@@ -18,8 +18,8 @@ func TestCustomDiff_OnLogin(t *testing.T) {
 	if miner.User() != "WALLET+abc" {
 		t.Fatalf("expected invalid suffix to remain unchanged")
 	}
-	if miner.customDiff != 10000 {
-		t.Fatalf("expected global diff fallback for invalid suffix, got %d", miner.customDiff)
+	if miner.customDiff != 0 {
+		t.Fatalf("expected invalid suffix to disable custom diff, got %d", miner.customDiff)
 	}
 
 	miner = &Miner{user: "WALLET"}
diff --git a/state_impl.go b/state_impl.go
index ab8903f..5977ba5 100644
--- a/state_impl.go
+++ b/state_impl.go
@@ -896,6 +896,7 @@ func parseLoginUser(login string, globalDiff uint64) (string, uint64) {
 		if parsed, err := strconv.ParseUint(login[plus+1:], 10, 64); err == nil {
 			return login[:plus], parsed
 		}
+		return login, 0
 	}
 	if globalDiff > 0 {
 		return login, globalDiff