diff --git a/phpBB/styles/prosilver/template/overall_header.html b/phpBB/styles/prosilver/template/overall_header.html
index 73ddc29efc..3a730f2daf 100644
--- a/phpBB/styles/prosilver/template/overall_header.html
+++ b/phpBB/styles/prosilver/template/overall_header.html
@@ -63,7 +63,7 @@
 </script>
 
 <link href="{T_THEME_PATH}/print.css?assets_version={T_ASSETS_VERSION}" rel="stylesheet" type="text/css" media="print" title="printonly" />
-<!-- IF S_ALLOW_CDN --><link href="http://fonts.googleapis.com/css?family=Open+Sans:600&amp;subset=latin,cyrillic-ext,latin-ext,cyrillic,greek-ext,greek,vietnamese" rel="stylesheet" type="text/css" media="screen, projection" /><!-- ENDIF -->
+<!-- IF S_ALLOW_CDN --><link href="//fonts.googleapis.com/css?family=Open+Sans:600&amp;subset=latin,cyrillic-ext,latin-ext,cyrillic,greek-ext,greek,vietnamese" rel="stylesheet" type="text/css" media="screen, projection" /><!-- ENDIF -->
 <link href="{T_STYLESHEET_LINK}" rel="stylesheet" type="text/css" media="screen, projection" />
 <link href="{T_STYLESHEET_LANG_LINK}" rel="stylesheet" type="text/css" media="screen, projection" />
 
diff --git a/phpBB/styles/prosilver/template/simple_header.html b/phpBB/styles/prosilver/template/simple_header.html
index c89c50570a..d198480d06 100644
--- a/phpBB/styles/prosilver/template/simple_header.html
+++ b/phpBB/styles/prosilver/template/simple_header.html
@@ -42,7 +42,7 @@
 </script>
 
 <link href="{T_THEME_PATH}/print.css?assets_version={T_ASSETS_VERSION}" rel="stylesheet" type="text/css" media="print" title="printonly" />
-<!-- IF S_ALLOW_CDN --><link href="http://fonts.googleapis.com/css?family=Open+Sans:600&amp;subset=latin,cyrillic-ext,latin-ext,cyrillic,greek-ext,greek,vietnamese" rel="stylesheet" type="text/css" media="screen, projection" /><!-- ENDIF -->
+<!-- IF S_ALLOW_CDN --><link href="//fonts.googleapis.com/css?family=Open+Sans:600&amp;subset=latin,cyrillic-ext,latin-ext,cyrillic,greek-ext,greek,vietnamese" rel="stylesheet" type="text/css" media="screen, projection" /><!-- ENDIF -->
 <link href="{T_STYLESHEET_LINK}" rel="stylesheet" type="text/css" media="screen, projection" />
 <link href="{T_STYLESHEET_LANG_LINK}" rel="stylesheet" type="text/css" media="screen, projection" />