diff --git a/ext/gd/gd.c b/ext/gd/gd.c
index b55cee9cc4e..e91b35a041a 100644
--- a/ext/gd/gd.c
+++ b/ext/gd/gd.c
@@ -2963,7 +2963,7 @@ static void _php_image_output(INTERNAL_FUNCTION_PARAMETERS, int image_type, char
 #if HAVE_GD_BUNDLED
 PHP_FUNCTION(imagexbm)
 {
-	_php_image_output_ctx(INTERNAL_FUNCTION_PARAM_PASSTHRU, PHP_GDIMG_TYPE_XBM, "GIF", gdImageXbmCtx);
+	_php_image_output_ctx(INTERNAL_FUNCTION_PARAM_PASSTHRU, PHP_GDIMG_TYPE_XBM, "XBM", gdImageXbmCtx);
 }
 #endif
 /* }}} */
@@ -2983,7 +2983,7 @@ PHP_FUNCTION(imagegif)
    Output PNG image to browser or file */
 PHP_FUNCTION(imagepng)
 {
-	_php_image_output_ctx(INTERNAL_FUNCTION_PARAM_PASSTHRU, PHP_GDIMG_TYPE_PNG, "GIF", gdImagePngCtxEx);
+	_php_image_output_ctx(INTERNAL_FUNCTION_PARAM_PASSTHRU, PHP_GDIMG_TYPE_PNG, "PNG", gdImagePngCtxEx);
 }
 /* }}} */
 #endif /* HAVE_GD_PNG */
@@ -2994,7 +2994,7 @@ PHP_FUNCTION(imagepng)
    Output PNG image to browser or file */
 PHP_FUNCTION(imagewebp)
 {
-	_php_image_output_ctx(INTERNAL_FUNCTION_PARAM_PASSTHRU, PHP_GDIMG_TYPE_WEBP, "GIF", gdImageWebpCtx);
+	_php_image_output_ctx(INTERNAL_FUNCTION_PARAM_PASSTHRU, PHP_GDIMG_TYPE_WEBP, "WEBP", gdImageWebpCtx);
 }
 /* }}} */
 #endif /* HAVE_GD_WEBP */
@@ -3005,7 +3005,7 @@ PHP_FUNCTION(imagewebp)
    Output JPEG image to browser or file */
 PHP_FUNCTION(imagejpeg)
 {
-	_php_image_output_ctx(INTERNAL_FUNCTION_PARAM_PASSTHRU, PHP_GDIMG_TYPE_JPG, "GIF", gdImageJpegCtx);
+	_php_image_output_ctx(INTERNAL_FUNCTION_PARAM_PASSTHRU, PHP_GDIMG_TYPE_JPG, "JPEG", gdImageJpegCtx);
 }
 /* }}} */
 #endif /* HAVE_GD_JPG */
@@ -3015,7 +3015,7 @@ PHP_FUNCTION(imagejpeg)
    Output WBMP image to browser or file */
 PHP_FUNCTION(imagewbmp)
 {
-	_php_image_output_ctx(INTERNAL_FUNCTION_PARAM_PASSTHRU, PHP_GDIMG_TYPE_WBM, "GIF", gdImageWBMPCtx);
+	_php_image_output_ctx(INTERNAL_FUNCTION_PARAM_PASSTHRU, PHP_GDIMG_TYPE_WBM, "WBMP", gdImageWBMPCtx);
 }
 /* }}} */
 #endif /* HAVE_GD_WBMP */