diff --git a/source/utf8/checked.h b/source/utf8/checked.h
index ff75eb7..e93819c 100644
--- a/source/utf8/checked.h
+++ b/source/utf8/checked.h
@@ -249,7 +249,7 @@ namespace utf8
     template <typename octet_iterator, typename u32bit_iterator>
     u32bit_iterator utf8to32 (octet_iterator start, octet_iterator end, u32bit_iterator result)
     {
-        while (start < end)
+        while (start != end)
             (*result++) = next(start, end);
 
         return result;
diff --git a/source/utf8/unchecked.h b/source/utf8/unchecked.h
index d3110cb..2f3eb4d 100644
--- a/source/utf8/unchecked.h
+++ b/source/utf8/unchecked.h
@@ -144,7 +144,7 @@ namespace utf8
         template <typename u16bit_iterator, typename octet_iterator>
         u16bit_iterator utf8to16 (octet_iterator start, octet_iterator end, u16bit_iterator result)
         {
-            while (start != end) {
+            while (start < end) {
                 uint32_t cp = next(start);
                 if (cp > 0xffff) { //make a surrogate pair
                     *result++ = static_cast<uint16_t>((cp >> 10)   + internal::LEAD_OFFSET);