--- a/tools/64vw.c	Mon May 27 08:35:35 2019 +0300
+++ b/tools/64vw.c	Mon May 27 10:47:46 2019 +0300
@@ -220,6 +220,7 @@
     SDL_Surface *surf, const DMC64ImageConvSpec *spec)
 {
     DMImage bmap;
+    BOOL charDataSet;
     int ret;
 
     memset(&bmap, 0, sizeof(bmap));
@@ -232,16 +233,21 @@
     if ((ret = dmSetDefaultC64Palette(&bmap)) != DMERR_OK)
         return ret;
 
-    if (cimage->charData->data == NULL)
-        cimage->charData = &setCharROM;
+    if (cimage->charData[0].data == NULL)
+    {
+        memcpy(&cimage->charData[0], &setCharROM, sizeof(DMC64MemBlock));
+        charDataSet = TRUE;
+    }
+    else
+        charDataSet = FALSE;
 
     if (fmt->format->convertFrom != NULL)
         ret = fmt->format->convertFrom(&bmap, cimage, fmt, spec);
     else
         ret = dmC64ConvertGenericBMP2Image(&bmap, cimage, fmt, spec);
 
-    if (cimage->charData == &setCharROM)
-        cimage->charData = NULL;
+    if (charDataSet)
+        memset(&cimage->charData[0], 0, sizeof(DMC64MemBlock));
 
     SDL_SetPaletteColors(surf->format->palette, (SDL_Color *) bmap.pal->colors, 0, bmap.pal->ncolors);
 
@@ -344,7 +350,8 @@
     dmMsg(1, "Using character ROM file '%s'.\n",
         optCharROMFilename);
 
-    if ((ret = dmReadDataFile(NULL, optCharROMFilename, &setCharROM.data, &setCharROM.size)) != DMERR_OK)
+    if ((ret = dmReadDataFile(NULL, optCharROMFilename,
+        &setCharROM.data, &setCharROM.size)) != DMERR_OK)
     {
         dmErrorMsg("Could not read character ROM from '%s'.\n",
             optCharROMFilename);