diff --git a/functions.php b/functions.php
index 0b3f7ba9f..4fadff8d9 100644
--- a/functions.php
+++ b/functions.php
@@ -1348,7 +1348,7 @@
 			return false;
 		} else {
 			return true;
-		} 
+		}
 	}
 
 	function file_is_locked($filename) {
@@ -2742,6 +2742,8 @@
 
 			}
 
+			print '[' . $_SESSION["client.userAgent"] . ']';
+
 			print "<td class=\"headlineActions$rtl_cpart\">
 				<ul class=\"headlineDropdownMenu\">
 				<li class=\"top2\">
diff --git a/modules/backend-rpc.php b/modules/backend-rpc.php
index 1a019af5b..b6823e2b7 100644
--- a/modules/backend-rpc.php
+++ b/modules/backend-rpc.php
@@ -185,6 +185,10 @@
 				print "<error error-code=\"0\"/>";
 				print_init_params($link);
 				print_runtime_info($link);
+
+				# assign client-passed params to session
+				$_SESSION["client.userAgent"] = $_GET["ua"];
+
 			}
 			print "</rpc-reply>";
 		}		
diff --git a/tt-rss.js b/tt-rss.js
index 66f6bff3d..0e4c15485 100644
--- a/tt-rss.js
+++ b/tt-rss.js
@@ -364,7 +364,9 @@ function init() {
 			debug('debug mode activated');
 		}
 
-		xmlhttp.open("GET", "backend.php?op=rpc&subop=sanityCheck", true);
+		var params = "&ua=" + param_escape(navigator.userAgent);
+
+		xmlhttp.open("GET", "backend.php?op=rpc&subop=sanityCheck" + params, true);
 		xmlhttp.onreadystatechange=backend_sanity_check_callback;
 		xmlhttp.send(null);