diff --git a/src/common/kiwix/indexer.cpp b/src/common/kiwix/indexer.cpp
index d2de96b23..dde989f47 100644
--- a/src/common/kiwix/indexer.cpp
+++ b/src/common/kiwix/indexer.cpp
@@ -5,7 +5,7 @@ namespace kiwix {
   /* Count word */
   unsigned int Indexer::countWords(const string &text) {
     unsigned int numWords = 1;
-    for(int i=0; i<text.size();) {
+    for(unsigned int i=0; i<text.size();) {
       while(i<text.size() && text[i] != ' ') {
 	i++;
       }