diff --git a/stb_image_write.h b/stb_image_write.h
index 271d4ac..a909e82 100644
--- a/stb_image_write.h
+++ b/stb_image_write.h
@@ -140,6 +140,7 @@ CREDITS:
       Ivan Tikhonov
       github:ignotion
       Adam Schackart
+      Andrew Kensler
 
 LICENSE
 
@@ -969,6 +970,23 @@ STBIWDEF unsigned char * stbi_zlib_compress(unsigned char *data, int data_len, i
       (void) stbiw__sbfree(hash_table[i]);
    STBIW_FREE(hash_table);
 
+   // store uncompressed instead if compression was worse
+   if (stbiw__sbn(out) > data_len + 2 + ((data_len+32766)/32767)*5) {
+      stbiw__sbn(out) = 2;  // truncate to DEFLATE 32K window and FLEVEL = 1
+      for (j = 0; j < data_len;) {
+         int blocklen = data_len - j;
+         if (blocklen > 32767) blocklen = 32767;
+         stbiw__sbpush(out, data_len - j == blocklen); // BFINAL = ?, BTYPE = 0 -- no compression
+         stbiw__sbpush(out, STBIW_UCHAR(blocklen)); // LEN
+         stbiw__sbpush(out, STBIW_UCHAR(blocklen >> 8));
+         stbiw__sbpush(out, STBIW_UCHAR(~blocklen)); // NLEN
+         stbiw__sbpush(out, STBIW_UCHAR(~blocklen >> 8));
+         memcpy(out+stbiw__sbn(out), data+j, blocklen);
+         stbiw__sbn(out) += blocklen;
+         j += blocklen;
+      }
+   }
+
    {
       // compute adler32 on input
       unsigned int s1=1, s2=0;
@@ -1599,6 +1617,8 @@ STBIWDEF int stbi_write_jpg(char const *filename, int x, int y, int comp, const
 #endif // STB_IMAGE_WRITE_IMPLEMENTATION
 
 /* Revision history
+      1.15  (          )
+             make Deflate code emit uncompressed blocks when it would otherwise expand
       1.14  (2020-02-02) updated JPEG writer to downsample chroma channels
       1.13
       1.12