diff --git a/pkg/wuffs/src/jpeg.zig b/pkg/wuffs/src/jpeg.zig
index 69628f582..c07278eed 100644
--- a/pkg/wuffs/src/jpeg.zig
+++ b/pkg/wuffs/src/jpeg.zig
@@ -55,7 +55,7 @@ pub fn decode(alloc: Allocator, data: []const u8) Error!ImageData {
 
     c.wuffs_base__pixel_config__set(
         &image_config.pixcfg,
-        c.WUFFS_BASE__PIXEL_FORMAT__RGBA_PREMUL,
+        c.WUFFS_BASE__PIXEL_FORMAT__RGBA_NONPREMUL,
         c.WUFFS_BASE__PIXEL_SUBSAMPLING__NONE,
         width,
         height,
@@ -95,16 +95,6 @@ pub fn decode(alloc: Allocator, data: []const u8) Error!ImageData {
         try check(log, &status);
     }
 
-    var frame_config: c.wuffs_base__frame_config = undefined;
-    {
-        const status = c.wuffs_jpeg__decoder__decode_frame_config(
-            decoder,
-            &frame_config,
-            &source_buffer,
-        );
-        try check(log, &status);
-    }
-
     {
         const status = c.wuffs_jpeg__decoder__decode_frame(
             decoder,
diff --git a/pkg/wuffs/src/png.zig b/pkg/wuffs/src/png.zig
index b85e4d747..1f37bb375 100644
--- a/pkg/wuffs/src/png.zig
+++ b/pkg/wuffs/src/png.zig
@@ -55,7 +55,7 @@ pub fn decode(alloc: Allocator, data: []const u8) Error!ImageData {
 
     c.wuffs_base__pixel_config__set(
         &image_config.pixcfg,
-        c.WUFFS_BASE__PIXEL_FORMAT__RGBA_PREMUL,
+        c.WUFFS_BASE__PIXEL_FORMAT__RGBA_NONPREMUL,
         c.WUFFS_BASE__PIXEL_SUBSAMPLING__NONE,
         width,
         height,
@@ -95,16 +95,6 @@ pub fn decode(alloc: Allocator, data: []const u8) Error!ImageData {
         try check(log, &status);
     }
 
-    var frame_config: c.wuffs_base__frame_config = undefined;
-    {
-        const status = c.wuffs_png__decoder__decode_frame_config(
-            decoder,
-            &frame_config,
-            &source_buffer,
-        );
-        try check(log, &status);
-    }
-
     {
         const status = c.wuffs_png__decoder__decode_frame(
             decoder,