diff --git a/src/pixie/fileformats/jpeg.nim b/src/pixie/fileformats/jpeg.nim
index 09100f2..4656ab4 100644
--- a/src/pixie/fileformats/jpeg.nim
+++ b/src/pixie/fileformats/jpeg.nim
@@ -315,9 +315,9 @@ proc decodeSOF0(state: var DecoderState) =
 
     # Allocate block data structures.
     component.blocks = newSeqWith(
-      component.width,
+      state.numMcuWide * component.yScale,
       newSeq[array[64, int16]](
-        component.height
+        state.numMcuHigh * component.xScale
       )
     )