diff --git a/ext/gd/gd.c b/ext/gd/gd.c
index 093daeac4199..938672ccc0c7 100644
--- a/ext/gd/gd.c
+++ b/ext/gd/gd.c
@@ -1358,24 +1358,6 @@ PHP_FUNCTION(imagetypes)
 }
 /* }}} */
 
-/* {{{ _php_ctx_getmbi */
-
-static int _php_ctx_getmbi(gdIOCtx *ctx)
-{
-	int i, mbi = 0;
-
-	do {
-		i = (ctx->getC)(ctx);
-		if (i < 0 || mbi > (INT_MAX >> 7)) {
-			return -1;
-		}
-		mbi = (mbi << 7) | (i & 0x7f);
-	} while (i & 0x80);
-
-	return mbi;
-}
-/* }}} */
-
 /* {{{ _php_image_type
  * Based on ext/standard/image.c
  */
@@ -1413,15 +1395,8 @@ static int _php_image_type(zend_string *data)
 		}
 	}
 
-	gdIOCtx *io_ctx;
-	io_ctx = gdNewDynamicCtxEx(8, ZSTR_VAL(data), 0);
-	if (io_ctx) {
-		if (_php_ctx_getmbi(io_ctx) == 0 && _php_ctx_getmbi(io_ctx) >= 0) {
-			io_ctx->gd_free(io_ctx);
-			return PHP_GDIMG_TYPE_WBM;
-		} else {
-			io_ctx->gd_free(io_ctx);
-		}
+	if (ZSTR_VAL(data)[0] == 0) {
+		return PHP_GDIMG_TYPE_WBM;
 	}
 
 	return -1;
diff --git a/ext/gd/tests/imagecreatefromstring.wbmp b/ext/gd/tests/imagecreatefromstring.wbmp
new file mode 100644
index 000000000000..f1af776b7f20
Binary files /dev/null and b/ext/gd/tests/imagecreatefromstring.wbmp differ
diff --git a/ext/gd/tests/imagecreatefromstring_wbmp.phpt b/ext/gd/tests/imagecreatefromstring_wbmp.phpt
new file mode 100644
index 000000000000..07bf3f7e196d
--- /dev/null
+++ b/ext/gd/tests/imagecreatefromstring_wbmp.phpt
@@ -0,0 +1,19 @@
+--TEST--
+imagecreatefromstring() - WBMP format
+--EXTENSIONS--
+gd
+--SKIPIF--
+<?php
+if (!(imagetypes() & IMG_WBMP)) die('skip GIF support required');
+?>
+--FILE--
+<?php
+// create an image from a WBMP string representation
+$im = imagecreatefromstring(file_get_contents(__DIR__ . '/imagecreatefromstring.wbmp'));
+var_dump(imagesx($im));
+var_dump(imagesy($im));
+
+?>
+--EXPECT--
+int(200)
+int(200)