diff --git a/apphandler.cpp b/apphandler.cpp
index 8ad2879..58f6868 100644
--- a/apphandler.cpp
+++ b/apphandler.cpp
@@ -486,15 +486,20 @@
     Revision r = {0};
     size_t val;
 
-    while (std::regex_search(s, m, fw_regex))
+    if (std::regex_search(s, m, fw_regex))
     {
+        if (m.size() < 3)
+        { // required m.size() to be at lease 3 to convert both major and minor
+            return -1;
+        }
+
         // convert major
         {
             std::string_view str = m[1].str();
             auto [ptr, ec]{std::from_chars(str.begin(), str.end(), val)};
             if (ec != std::errc() || ptr != str.begin() + str.size())
             { // failed to convert major string
-                continue;
+                return -1;
             }
             r.major = val & 0x7F;
         }
@@ -505,7 +510,7 @@
             auto [ptr, ec]{std::from_chars(str.begin(), str.end(), val)};
             if (ec != std::errc() || ptr != str.begin() + str.size())
             { // failed to convert minor string
-                continue;
+                return -1;
             }
             r.minor = val & 0xFF;
         }