diff --git a/ext/zlib/tests/bug61820.phpt b/ext/zlib/tests/bug61820.phpt
new file mode 100644
index 00000000000..6f33b545531
--- /dev/null
+++ b/ext/zlib/tests/bug61820.phpt
@@ -0,0 +1,23 @@
+--TEST--
+bug #61820 using ob_gzhandler will complain about headers already sent when no compression
+--SKIPIF--
+<?php
+extension_loaded("zlib") or die("skip");
+?>
+--FILE--
+<?php
+ob_start('ob_gzhandler');
+
+echo "Hi there.\n";
+ob_flush();
+flush();
+
+echo "This is confusing...\n";
+ob_flush();
+flush();
+?>
+DONE
+--EXPECT--
+Hi there.
+This is confusing...
+DONE
diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index d472573b79e..545979dc9cf 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -187,7 +187,9 @@ static int php_zlib_output_handler(void **handler_context, php_output_context *o
 			-Vary: $ HTTP_ACCEPT_ENCODING=gzip ./sapi/cgi/php <<<'<?php ob_start("ob_gzhandler"); echo "foo\n"; ob_end_clean();'
 			-Vary: $ HTTP_ACCEPT_ENCODING= ./sapi/cgi/php <<<'<?php ob_start("ob_gzhandler"); echo "foo\n"; ob_end_clean();'
 		*/
-		if (output_context->op != (PHP_OUTPUT_HANDLER_START|PHP_OUTPUT_HANDLER_CLEAN|PHP_OUTPUT_HANDLER_FINAL)) {
+		if ((output_context->op & PHP_OUTPUT_HANDLER_START)
+		&&	(output_context->op != (PHP_OUTPUT_HANDLER_START|PHP_OUTPUT_HANDLER_CLEAN|PHP_OUTPUT_HANDLER_FINAL))
+		) {
 			sapi_add_header_ex(ZEND_STRL("Vary: Accept-Encoding"), 1, 1 TSRMLS_CC);
 		}
 		return FAILURE;