diff --git a/src/samplesrc/dcgrtest.pla b/src/samplesrc/dcgrtest.pla
index e2c6425..90dd2df 100644
--- a/src/samplesrc/dcgrtest.pla
+++ b/src/samplesrc/dcgrtest.pla
@@ -256,7 +256,8 @@ def dcgrTest#0
     //
     // Use back buffer for tile set buffer
     //
-    for j = 0 to 6
+    j = 0
+    while ^$C000 < 128
         dcgrMemBl7Tile(0, 0, backblk,       sprite7[j], sprite7span)
         dcgrMemBl7Tile(1, 0, backblk + 32,  sprite7[j], sprite7span)
         dcgrMemBl7Tile(2, 0, backblk + 64,  sprite7[j], sprite7span)
@@ -276,7 +277,9 @@ def dcgrTest#0
             dcgrTiles(0, i,     @tilestr,      20, backblk)
             dcgrTiles(0, i + 1, @tilestr + 20, 20, backblk)
         next
-    next
+        j++
+        if j > 6; j = 0; fin
+    loop
     getc
     //
     // Lines