diff --git a/modules/libpr0n/src/imgRequest.cpp b/modules/libpr0n/src/imgRequest.cpp
index dd2de0f1114..1fb1ff2bb86 100644
--- a/modules/libpr0n/src/imgRequest.cpp
+++ b/modules/libpr0n/src/imgRequest.cpp
@@ -808,86 +808,6 @@ imgRequest::SniffMimeType(const char *buf, PRUint32 len)
     return;
   }
 
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  // ALWAYS KEEP THIS SNIFF AT THE END OF THE FILE!
-  if (len >= 4 && 
-      ((PRUint16*)buf)[0]==0 &&
-      (LITTLE_TO_NATIVE16(((PRUint16*)buf)[1]))==1) {
-    mContentType = nsCRT::strndup("image/x-icon", 12);
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = nsCRT::strndup("image/bmp", 9);
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = nsCRT::strndup("image/x-icon", 12);
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = nsCRT::strndup("image/bmp", 9);
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = nsCRT::strndup("image/x-icon", 12);
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = nsCRT::strndup("image/bmp", 9);
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = nsCRT::strndup("image/x-icon", 12);
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = nsCRT::strndup("image/bmp", 9);
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = nsCRT::strndup("image/x-icon", 12);
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = nsCRT::strndup("image/bmp", 9);
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = nsCRT::strndup("image/x-icon", 12);
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = nsCRT::strndup("image/bmp", 9);
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = nsCRT::strndup("image/x-icon", 12);
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = nsCRT::strndup("image/bmp", 9);
-    return;
-  }
-
   // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
   if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
     mContentType = nsCRT::strndup("image/x-icon", 12);
diff --git a/netwerk/streamconv/converters/nsUnknownDecoder.cpp b/netwerk/streamconv/converters/nsUnknownDecoder.cpp
index faabfcf41ff..dedaeb32733 100644
--- a/netwerk/streamconv/converters/nsUnknownDecoder.cpp
+++ b/netwerk/streamconv/converters/nsUnknownDecoder.cpp
@@ -413,86 +413,6 @@ void nsUnknownDecoder::SniffForImageMimeType(const char *buf, PRUint32 len)
     return;
   }
 
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  // ALWAYS KEEP THIS SNIFF AT THE END OF THE FILE!
-  if (len >= 4 && 
-      ((PRUint16*)buf)[0]==0 &&
-      (LITTLE_TO_NATIVE16(((PRUint16*)buf)[1]))==1) {
-    mContentType = NS_LITERAL_CSTRING("image/x-icon");
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = NS_LITERAL_CSTRING("image/bmp");
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = NS_LITERAL_CSTRING("image/x-icon");
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = NS_LITERAL_CSTRING("image/bmp");
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = NS_LITERAL_CSTRING("image/x-icon");
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = NS_LITERAL_CSTRING("image/bmp");
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = NS_LITERAL_CSTRING("image/x-icon");
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = NS_LITERAL_CSTRING("image/bmp");
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = NS_LITERAL_CSTRING("image/x-icon");
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = NS_LITERAL_CSTRING("image/bmp");
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = NS_LITERAL_CSTRING("image/x-icon");
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = NS_LITERAL_CSTRING("image/bmp");
-    return;
-  }
-
-  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
-  if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
-    mContentType = NS_LITERAL_CSTRING("image/x-icon");
-    return;
-  }
-
-  if (len >= 2 && !nsCRT::strncmp(buf, "BM", 2)) {
-    mContentType = NS_LITERAL_CSTRING("image/bmp");
-    return;
-  }
-
   // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
   if (len >= 4 && !nsCRT::memcmp(buf, "\000\000\001\000", 4)) {
     mContentType = NS_LITERAL_CSTRING("image/x-icon");