diff --git a/sane/scanner.cpp b/sane/scanner.cpp
index c4d4023..c152720 100644
--- a/sane/scanner.cpp
+++ b/sane/scanner.cpp
@@ -391,6 +391,8 @@ bool scanner::is_belong_serial(int vid, int pid, SCANNERID serial)
 				GET_SCANNER_PID(serial) == 0x404)	// OEM_CANGTIAN
 				return true;
 		}
+
+		return false;
 	}
 	else if (vid == PRODUCT_VENDOR_HG1)
 	{
@@ -421,9 +423,9 @@ bool scanner::is_belong_serial(int vid, int pid, SCANNERID serial)
 				return pid == 0x8730 || pid == 0x8739;
 			}
 		}
+		return false;
 	}
-
-	return false;
+	return true;
 }
 void scanner::get_scanner_name(SCANNERID id, std::vector<std::string>& names)
 {