diff --git a/ext/filter/logical_filters.c b/ext/filter/logical_filters.c
index 0b27a641f2b..52dcb504ecb 100644
--- a/ext/filter/logical_filters.c
+++ b/ext/filter/logical_filters.c
@@ -467,7 +467,7 @@ void php_filter_validate_url(PHP_INPUT_FILTER_PARAM_DECL) /* {{{ */
 		s = url->host;
 
 		while (s < e) {
-			if (!isalnum((int)*(unsigned char *)s) && *s != '_' && *s != '.') {
+			if (!isalnum((int)*(unsigned char *)s) && *s != '-' && *s != '.') {
 				goto bad_url;
 			}
 			s++;
diff --git a/ext/filter/tests/bug51192.phpt b/ext/filter/tests/bug51192.phpt
new file mode 100644
index 00000000000..96c67eae1de
--- /dev/null
+++ b/ext/filter/tests/bug51192.phpt
@@ -0,0 +1,13 @@
+--TEST--
+bug 51192, FILTER_VALIDATE_URL will invalidate a hostname that includes '-'
+--SKIPIF--
+<?php if (!extension_loaded("filter")) die("skip"); ?>
+--FILE--
+<?php
+var_dump(filter_var('http://example.com/path', FILTER_VALIDATE_URL));
+var_dump(filter_var('http://exa-mple.com/path', FILTER_VALIDATE_URL));
+var_dump(filter_var('http://exa_mple.com/path', FILTER_VALIDATE_URL));
+--EXPECT--	
+string(23) "http://example.com/path"
+string(24) "http://exa-mple.com/path"
+bool(false)