diff --git a/openvpn/common/clamp.hpp b/openvpn/common/clamp.hpp
index 9ab4f510..6a60fc0c 100644
--- a/openvpn/common/clamp.hpp
+++ b/openvpn/common/clamp.hpp
@@ -36,4 +36,13 @@ namespace openvpn {
       return value;
   }
 
+  // like clamp() above, but only clamp non-zero values
+  template <typename T>
+  T clamp_nonzero(T value, T low, T high)
+  {
+    if (value)
+      return clamp(value, low, high);
+    else
+      return value;
+  }
 }