diff --git a/include/cppjieba/FullSegment.hpp b/include/cppjieba/FullSegment.hpp
index fc7aab2..ef314d7 100644
--- a/include/cppjieba/FullSegment.hpp
+++ b/include/cppjieba/FullSegment.hpp
@@ -48,17 +48,17 @@ class FullSegment: public SegmentBase {
   void Cut(RuneStrArray::const_iterator begin, 
         RuneStrArray::const_iterator end, 
         vector<WordRange>& res) const {
-    //resut of searching in trie tree
+    // resut of searching in trie tree
     LocalVector<pair<size_t, const DictUnit*> > tRes;
 
-    //max index of res's words
-    int maxIdx = 0;
+    // max index of res's words
+    size_t maxIdx = 0;
 
     // always equals to (uItr - begin)
-    int uIdx = 0;
+    size_t uIdx = 0;
 
-    //tmp variables
-    int wordLen = 0;
+    // tmp variables
+    size_t wordLen = 0;
     assert(dictTrie_);
     vector<struct Dag> dags;
     dictTrie_->Find(begin, end, dags);
diff --git a/include/cppjieba/Unicode.hpp b/include/cppjieba/Unicode.hpp
index 87de505..b064c4a 100644
--- a/include/cppjieba/Unicode.hpp
+++ b/include/cppjieba/Unicode.hpp
@@ -142,7 +142,7 @@ inline RuneStrLite DecodeRuneInString(const char* str, size_t len) {
 inline bool DecodeRunesInString(const char* s, size_t len, RuneStrArray& runes) {
   runes.clear();
   runes.reserve(len / 2);
-  for (size_t i = 0, j = 0; i < len;) {
+  for (uint32_t i = 0, j = 0; i < len;) {
     RuneStrLite rp = DecodeRuneInString(s + i, len - i);
     if (rp.len == 0) {
       runes.clear();