diff --git a/sapi/cgi/cgi_main.c b/sapi/cgi/cgi_main.c
index 98981c0ae32..c0e02664eeb 100644
--- a/sapi/cgi/cgi_main.c
+++ b/sapi/cgi/cgi_main.c
@@ -1689,9 +1689,9 @@ static void add_response_header(sapi_header_struct *h, zval *return_value) /* {{
 			len = p - h->header;
 		}
 		if (len > 0) {
-			do {
+			while (len != 0 && (h->header[len-1] == ' ' || h->header[len-1] == '\t')) {
 				len--;
-			} while (len != 0 && (h->header[len-1] == ' ' || h->header[len-1] == '\t'));
+			}
 			if (len) {
 				s = do_alloca(len + 1, use_heap);
 				memcpy(s, h->header, len);
diff --git a/sapi/cgi/tests/apache_response_headers.phpt b/sapi/cgi/tests/apache_response_headers.phpt
new file mode 100644
index 00000000000..2964ac7bc71
--- /dev/null
+++ b/sapi/cgi/tests/apache_response_headers.phpt
@@ -0,0 +1,48 @@
+--TEST--
+apache_response_headers()
+--SKIPIF--
+<?php
+include "skipif.inc";
+?>
+--FILE--
+<?php
+include "include.inc";
+
+$php = get_cgi_path();
+reset_env_vars();
+
+$test_file = dirname(__FILE__) . DIRECTORY_SEPARATOR ."apache_response_headers.test.php";
+
+$code  = '<?php';
+$code .= '
+header( "X-Robots-Tag : noindex,nofollow,noarchive" );
+header( "Content-type: text/html; charset=UTF-8" );
+header( "Bad-header" );
+header( " : " );
+header( ":" );
+flush();
+
+var_dump( apache_response_headers() );
+?>
+';
+
+file_put_contents( $test_file, $code );
+
+passthru( "$php -n -q " . escapeshellarg( $test_file ) );
+
+?>
+===DONE===
+--CLEAN--
+<?php
+@unlink( dirname(__FILE__) . DIRECTORY_SEPARATOR ."apache_response_headers.test.php" );
+?>
+--EXPECTF--
+array(3) {
+  ["X-Powered-By"]=>
+  string(%d) "PHP/%s"
+  ["X-Robots-Tag"]=>
+  string(26) "noindex,nofollow,noarchive"
+  ["Content-type"]=>
+  string(24) "text/html; charset=UTF-8"
+}
+===DONE===