diff --git a/ext/iconv/iconv.c b/ext/iconv/iconv.c
index 2a272b49aba..c3b6daebab7 100644
--- a/ext/iconv/iconv.c
+++ b/ext/iconv/iconv.c
@@ -1762,10 +1762,10 @@ static php_iconv_err_t _php_iconv_mime_decode(smart_str *pretval, const char *st
 							if ((mode & PHP_ICONV_MIME_DECODE_CONTINUE_ON_ERROR)) {
 								/* pass the entire chunk through the converter */
 								err = _php_iconv_appendl(pretval, encoded_word, (size_t)(p1 - encoded_word), cd_pl); 
-								if (err != PHP_ICONV_ERR_SUCCESS) {
-									goto out;
-								}
 								encoded_word = NULL;
+								if (err != PHP_ICONV_ERR_SUCCESS) {
+									break;
+								}
 							} else {
 								goto out;
 							}
diff --git a/ext/iconv/tests/bug51250.phpt b/ext/iconv/tests/bug51250.phpt
new file mode 100644
index 00000000000..fd2e53b97a2
--- /dev/null
+++ b/ext/iconv/tests/bug51250.phpt
@@ -0,0 +1,29 @@
+--TEST--
+Bug #51250 (iconv_mime_decode() does not ignore malformed Q-encoded words)
+--SKIPIF--
+<?php extension_loaded('iconv') or die('skip iconv extension is not available'); ?>
+--FILE--
+<?php
+$m = ICONV_MIME_DECODE_CONTINUE_ON_ERROR;
+
+var_dump(iconv_mime_decode("Legal encoded-word: =?utf-8?B?Kg==?= .", $m));
+var_dump(iconv_mime_decode("Legal encoded-word: =?utf-8?Q?*?= .", $m));
+var_dump(iconv_mime_decode("Illegal encoded-word: =?utf-8?B?".chr(0xA1)."?= .", $m));
+var_dump(iconv_mime_decode("Illegal encoded-word: =?utf-8?Q?".chr(0xA1)."?= .", $m));
+
+var_dump(iconv_mime_decode("Legal encoded-word: =?utf-8?B?Kg==?= ."));
+var_dump(iconv_mime_decode("Legal encoded-word: =?utf-8?Q?*?= ."));
+var_dump(iconv_mime_decode("Illegal encoded-word: =?utf-8?B?".chr(0xA1)."?= ."));
+var_dump(iconv_mime_decode("Illegal encoded-word: =?utf-8?Q?".chr(0xA1)."?= ."));
+?>
+--EXPECTF--
+string(23) "Legal encoded-word: * ."
+string(23) "Legal encoded-word: * ."
+string(24) "Illegal encoded-word:  ."
+string(23) "Illegal encoded-word: ."
+string(23) "Legal encoded-word: * ."
+string(23) "Legal encoded-word: * ."
+string(24) "Illegal encoded-word:  ."
+
+Notice: iconv_mime_decode(): Detected an illegal character in input string in %s on line %d
+bool(false)