diff --git a/dlls/mpr/pwcache.c b/dlls/mpr/pwcache.c
index aa09522a5f9..f330a2a000a 100644
--- a/dlls/mpr/pwcache.c
+++ b/dlls/mpr/pwcache.c
@@ -45,7 +45,7 @@ static inline signed char ctox( CHAR x )
         return x - '0';
     if( ( x >= 'A' ) && ( x <= 'F' ) )
         return x - 'A' + 10;
-    if( ( x >= 'a' ) && ( x <= 'a' ) )
+    if( ( x >= 'a' ) && ( x <= 'f' ) )
         return x - 'a' + 10;
     return -1;
 }