--- CV/CV.xs	2021/07/15 00:41:44	1.60
+++ CV/CV.xs	2021/07/25 11:24:48	1.61
@@ -453,6 +453,35 @@
           RETVAL = "image/png";
         else if (data_len >= sizeof (jxl_header) && memcmp (data, jxl_header, sizeof (jxl_header)) == 0)
           RETVAL = "image/jxl";
+        else if (data_len >= 13
+                 && data[0] == 'G'
+                 && data[1] == 'I'
+                 && data[2] == 'F'
+                 && data[3] == '8'
+                 //&& (data[4] == '7' || data[4] == '9')
+                 && data[5] == 'a')
+          {
+            RETVAL = "image/gif";
+
+            // now see if its animated - we require the netscape application header for this
+            int ofs = 13;
+
+            if (data[10] & 0x80)
+              ofs += (1 << ((data[10] & 7) + 1)) * 3;
+
+            if (data_len >= ofs + 2 + 1 + 11)
+              {
+                // skip a rare first graphic control extension block
+                // we assume there is exactly one block
+                if (data[ofs] == 0x21 && data[ofs + 1] == 0xf9)
+                  ofs += 3 + data[ofs + 2] + 1;
+
+                if (data_len >= ofs + 2 + 1 + 11)
+                  if (!memcmp (data + ofs, "\x21\xff\x0bNETSCAPE2.0", sizeof ("\x21\xff\x0bNETSCAPE2.0") - 1))
+                    RETVAL = "video/gif";
+              }
+          }
+
         else
           XSRETURN_UNDEF;
 }