diff --git a/src/MultibyteStringStream.php b/src/MultibyteStringStream.php
index 75eda94..48abf98 100644
--- a/src/MultibyteStringStream.php
+++ b/src/MultibyteStringStream.php
@@ -58,19 +58,23 @@ public function onClose() {
     }
 
     public function filter($in, $out, &$consumed, $closing) {
-        $buffer = &$this->buffer;
+        $buffer  = &$this->buffer;
+        $pass_on = false;
 
         while ($bucket = stream_bucket_make_writeable($in)) {
             $encoded_data = $buffer . $bucket->data;
             $valid_chars  = $this->truncateInvalidCharacters($encoded_data);
             $buffer       = substr($encoded_data, strlen($valid_chars));
 
-            $decoded_data = $this->convert($valid_chars, $this->to_encoding);
+            $consumed += $bucket->datalen;
 
-            $bucket->data = $decoded_data;
-            $consumed     = $consumed + $bucket->datalen;
+            if (!empty($valid_chars)) {
+                $bucket->data = $this->convert($valid_chars, $this->to_encoding);
 
-            stream_bucket_append($out, $bucket);
+                stream_bucket_append($out, $bucket);
+
+                $pass_on = true;
+            }
         }
 
         if ($closing && !empty($buffer)) {
@@ -82,13 +86,11 @@ public function filter($in, $out, &$consumed, $closing) {
             $buffer    = '';
 
             stream_bucket_append($out, $bucket);
-        }
 
-        if (!empty($buffer)) {
-            return PSFS_FEED_ME;
+            $pass_on = true;
         }
 
-        return PSFS_PASS_ON;
+        return $pass_on ? PSFS_PASS_ON : PSFS_FEED_ME;
     }
 
     private function truncateInvalidCharacters($data) {
diff --git a/tests/MultibyteStringStreamTest.php b/tests/MultibyteStringStreamTest.php
index 0f69f59..bc451db 100644
--- a/tests/MultibyteStringStreamTest.php
+++ b/tests/MultibyteStringStreamTest.php
@@ -118,6 +118,30 @@ public function testMultibyteEdgeHandling() {
         );
     }
 
+    public function testMultibyteEdgeHandlingAfterBucketWrite() {
+        $output     = fopen('php://memory', 'w+');
+        $filtername = 'convert.mbstring.UTF-8/UTF-8';
+
+        stream_filter_append($output, $filtername, STREAM_FILTER_WRITE);
+
+        $bucket_data    = str_pad('', 128, 'abc');
+        $malformed_data = substr("🍩", 0, 2);
+
+        fwrite($output, $bucket_data . $malformed_data);
+        fflush($output);
+
+        rewind($output);
+
+        $expected = $bucket_data;
+        $result   = stream_get_contents($output);
+
+        $this->assertSame(
+            $expected,
+            $result,
+            'Failed to preserve valid data'
+        );
+    }
+
     public function testCloseInvalidData() {
         $output     = fopen('php://output', 'w');
         $filtername = 'convert.mbstring.UTF-8/UTF-8';