diff --git a/src/utility.cpp b/src/utility.cpp
index 992c329..e50b0fe 100644
--- a/src/utility.cpp
+++ b/src/utility.cpp
@@ -332,8 +332,8 @@ int Natural::compare(const std::string &s1, const std::string &s2) {
     }
   }
 
-  if(i1 == s1.size()) {
-    if(i2 == s2.size())
+  if(i1 >= s1.size()) {
+    if(i2 >= s2.size())
       return 0;
     return -1;
   }