--- src/contribs-lib/CLucene/analysis/PorterStemmer.cpp
+++ src/contribs-lib/CLucene/analysis/PorterStemmer.cpp
@@ -94,7 +94,7 @@
     return true;
   }
 
-  bool PorterStemmer::ends(TCHAR *s) {
+  bool PorterStemmer::ends(const TCHAR *s) {
 	size_t l = _tcslen(s);
     size_t o = k-l+1;
     if (o < k0)
--- src/contribs-lib/CLucene/analysis/PorterStemmer.h
+++ src/contribs-lib/CLucene/analysis/PorterStemmer.h
@@ -68,7 +68,7 @@
   */
    bool cvc(size_t i);
 
-  bool ends(TCHAR *s);
+  bool ends(const TCHAR *s);
 
   /* setto(s) sets (j+1),...k to the characters in the string s, readjusting
      k. */