diff --git a/include/window.h b/include/window.h
index 8c2dae99..d1f3577b 100644
--- a/include/window.h
+++ b/include/window.h
@@ -4584,17 +4584,16 @@ typedef unsigned long RES_KEY;
 /* define the incore res type */
 typedef struct _INNER_RES {
     RES_KEY key;
-    Uint8* data;
+    const Uint8* data;
     int data_len;
 
-    /* special param recognized by the TYPE_OPS
-     * normal is null. 
-     * is the data is a mem of raw png, jpeg, bmp
+    /* The special param recognized by the TYPE_OPS normally it is NULL.
+     * If data is the data is a mem of raw png, jpeg, bmp
      * and so on, it should be the extention name
-     * of the filename. eg. 
+     * of the filename. eg.
      * INNER_RES res[]= { ... { ..., ... ,.., "png" } .. };
      * */
-    void* additional;
+    const void* additional;
 } INNER_RES;
 
 /* the type of resource */
diff --git a/src/sysres/resmgr.c b/src/sysres/resmgr.c
index a442f154..dc3de550 100644
--- a/src/sysres/resmgr.c
+++ b/src/sysres/resmgr.c
@@ -928,11 +928,12 @@ static void* img_get_res_data(RESOURCE* res, int src_type, DWORD usr_param)
                 INNER_RES* inner = res->source.inner;
                 if(inner->additional == NULL) //raw bitmap
                 {
-                    res->data = inner->data;
+                    res->data = (void*)inner->data;
                 }
                 else {
                     BITMAP *pbmp = NEW(BITMAP);
-                    if(LoadBitmapFromMem((HDC)usr_param, pbmp, inner->data, inner->data_len, (const char*)inner->additional) != 0)
+                    if(LoadBitmapFromMem((HDC)usr_param, pbmp, inner->data,
+                            inner->data_len, (const char*)inner->additional) != 0)
                     {
                         DELETE(pbmp);
                         return NULL;
@@ -1177,7 +1178,7 @@ static void* etc_get_res_data(RESOURCE* res, int src_type, DWORD usr_param)
             break;
         }
         case REF_SRC_INNER:
-            res->data = res->source.inner->data;
+            res->data = (void*)res->source.inner->data;
             break;
         default:
             return NULL;