diff --git a/stb_image.h b/stb_image.h
index 71bd506..2fced29 100644
--- a/stb_image.h
+++ b/stb_image.h
@@ -2158,7 +2158,7 @@ static int stbi__jpeg_decode_block(stbi__jpeg *j, short data[64], stbi__huffman
 
    if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
    t = stbi__jpeg_huff_decode(j, hdc);
-   if (t < 0) return stbi__err("bad huffman code","Corrupt JPEG");
+   if (t < 0 || t > 15) return stbi__err("bad huffman code","Corrupt JPEG");
 
    // 0 all the ac values now so we can do it 32-bits at a time
    memset(data,0,64*sizeof(data[0]));
@@ -2215,7 +2215,7 @@ static int stbi__jpeg_decode_block_prog_dc(stbi__jpeg *j, short data[64], stbi__
       // first scan for DC coefficient, must be first
       memset(data,0,64*sizeof(data[0])); // 0 all the ac values now
       t = stbi__jpeg_huff_decode(j, hdc);
-      if (t == -1) return stbi__err("can't merge dc and ac", "Corrupt JPEG");
+      if (t < 0 || t > 15) return stbi__err("can't merge dc and ac", "Corrupt JPEG");
       diff = t ? stbi__extend_receive(j, t) : 0;
 
       dc = j->img_comp[b].dc_pred + diff;