diff --git a/include/assimp/types.h b/include/assimp/types.h
index 0e50ed0ae..99527dcc2 100644
--- a/include/assimp/types.h
+++ b/include/assimp/types.h
@@ -305,7 +305,7 @@ struct aiString {
 
     /** Copy a const char* to the aiString */
     void Set(const char *sz) {
-        const ai_int32 len = (ai_uint32)::strlen(sz);
+        ai_int32 len = (ai_uint32)::strlen(sz);
         if (len > (ai_int32)MAXLEN - 1) {
             len = (ai_int32) MAXLEN - 1;
         }