diff --git a/functions.js b/functions.js
index 9e65a6dce..56285b731 100644
--- a/functions.js
+++ b/functions.js
@@ -577,55 +577,6 @@ function parse_counters(reply, scheduled_call) {
 
 } */
 
-function handle_rpc_reply(transport, scheduled_call) {
-	try {
-		if (offline_mode) return false;
-
-		if (!transport.responseText && db) {
-			offlineConfirmModeChange();
-			return false;
-		} 
-
-		if (transport.responseXML) {
-
-			if (!transport_error_check(transport)) return false;
-
-			var message = transport.responseXML.getElementsByTagName("message")[0];
-
-			if (message) {
-				message = message.firstChild.nodeValue;
-
-				if (message == "UPDATE_COUNTERS") {
-					setInitParam("last_article_id", -1);
-					_force_scheduled_update = true;
-				}
-			}
-
-			var counters = transport.responseXML.getElementsByTagName("counters")[0];
-	
-			if (counters)
-				parse_counters(counters, scheduled_call);
-
-			var runtime_info = transport.responseXML.getElementsByTagName("runtime-info")[0];
-
-			if (runtime_info)
-				parse_runtime_info(runtime_info);
-
-			if (feedsSortByUnread())
-				resort_feedlist();
-
-			hideOrShowFeeds(getInitParam("hide_read_feeds") == 1);
-
-		} else {
-			notify_error("Error communicating with server.");
-		}
-
-	} catch (e) {
-		exception_error("handle_rpc_reply", e, transport);
-	}
-
-	return true;
-}
 
 function get_feed_unread(id) {
 	try {
@@ -1290,20 +1241,45 @@ function createFilter() {
 			alert(__("Can't add filter: nothing to match on."));
 			return false;
 		}
+
+		var query = "?op=rpc&subop=verifyRegexp&reg_exp=" + param_escape(reg_exp);
+
+		notify_progress("Verifying regular expression...");
+
+		new Ajax.Request("backend.php",	{
+				parameters: query,
+				onComplete: function(transport) {
+					handle_rpc_reply(transport);
+
+					var response = transport.responseXML;
+
+					if (response) {
+						var s = response.getElementsByTagName("status")[0].firstChild.nodeValue;
 	
-		var query = Form.serialize("filter_add_form");
-	
-		// we can be called from some other tab in Prefs		
-		if (typeof active_tab != 'undefined' && active_tab) {
-			active_tab = "filterConfig";
-		}
-	
-		new Ajax.Request("backend.php?" + query, {
-			onComplete: function (transport) {
-				infobox_submit_callback2(transport);
+						notify('');
+
+						if (s == "INVALID") {
+							alert("Match regular expression seems to be invalid.");
+							return;
+						} else {
+
+							var query = Form.serialize("filter_add_form");
+						
+							// we can be called from some other tab in Prefs		
+							if (typeof active_tab != 'undefined' && active_tab) {
+								active_tab = "filterConfig";
+							}
+						
+							new Ajax.Request("backend.php?" + query, {
+								onComplete: function (transport) {
+									infobox_submit_callback2(transport);
+								} });
+							
+							return true;
+						}
+					}
+
 			} });
-		
-		return true;
 
 	} catch (e) {
 		exception_error("createFilter", e);
diff --git a/modules/backend-rpc.php b/modules/backend-rpc.php
index 8eacb199e..6792fae7f 100644
--- a/modules/backend-rpc.php
+++ b/modules/backend-rpc.php
@@ -1128,6 +1128,22 @@
 			return;
 		}
 
+		if ($subop == "verifyRegexp") {
+			$reg_exp = $_REQUEST["reg_exp"];
+
+			print "<rpc-reply><status>";
+
+			if (@preg_match("/$reg_exp/i", "TEST") === false) {
+				print "INVALID";
+			} else {
+				print "OK";
+			}
+
+			print "</status></rpc-reply>";
+
+			return;
+		}
+
 		print "<rpc-reply><error>Unknown method: $subop</error></rpc-reply>";
 	}
 ?>
diff --git a/prefs.js b/prefs.js
index ed8d1679c..2d8b02942 100644
--- a/prefs.js
+++ b/prefs.js
@@ -764,19 +764,44 @@ function userEditSave() {
 
 
 function filterEditSave() {
-
 	try {
+		var reg_exp = document.forms["filter_edit_form"].reg_exp.value;
 
-		notify_progress("Saving filter...");
-	
-		var query = "?" + Form.serialize("filter_edit_form");
-	
-		closeInfoBox();
+		var query = "?op=rpc&subop=verifyRegexp&reg_exp=" + param_escape(reg_exp);
+
+		notify_progress("Verifying regular expression...");
 
 		new Ajax.Request("backend.php",	{
 				parameters: query,
 				onComplete: function(transport) {
-						filterlist_callback2(transport);
+					handle_rpc_reply(transport);
+
+					var response = transport.responseXML;
+
+					if (response) {
+						var s = response.getElementsByTagName("status")[0].firstChild.nodeValue;
+	
+						notify('');
+
+						if (s == "INVALID") {
+							alert("Match regular expression seems to be invalid.");
+							return;
+						} else {
+
+							var query = "?" + Form.serialize("filter_edit_form");
+					
+							notify_progress("Saving filter...");
+			
+							Form.disable("filter_edit_form");
+
+							new Ajax.Request("backend.php",	{
+									parameters: query,
+									onComplete: function(transport) {
+											closeInfoBox();
+											filterlist_callback2(transport);
+								} });
+						}
+					}
 			} });
 
 	} catch (e) {
@@ -2099,4 +2124,20 @@ function clearFeedAccessKeys() {
 	return false;
 }
 
+function handle_rpc_reply(transport, scheduled_call) {
+	try {
+		if (transport.responseXML) {
+
+			if (!transport_error_check(transport)) return false;
+
+		} else {
+			notify_error("Error communicating with server.");
+		}
+
+	} catch (e) {
+		exception_error("handle_rpc_reply", e, transport);
+	}
+
+	return true;
+}
 
diff --git a/tt-rss.js b/tt-rss.js
index b97a19aa1..e755faf70 100644
--- a/tt-rss.js
+++ b/tt-rss.js
@@ -1250,3 +1250,53 @@ function showFeedsWithErrors() {
 	displayDlg('feedUpdateErrors');
 }
 
+function handle_rpc_reply(transport, scheduled_call) {
+	try {
+		if (offline_mode) return false;
+
+		if (!transport.responseText && db) {
+			offlineConfirmModeChange();
+			return false;
+		} 
+
+		if (transport.responseXML) {
+
+			if (!transport_error_check(transport)) return false;
+
+			var message = transport.responseXML.getElementsByTagName("message")[0];
+
+			if (message) {
+				message = message.firstChild.nodeValue;
+
+				if (message == "UPDATE_COUNTERS") {
+					setInitParam("last_article_id", -1);
+					_force_scheduled_update = true;
+				}
+			}
+
+			var counters = transport.responseXML.getElementsByTagName("counters")[0];
+	
+			if (counters)
+				parse_counters(counters, scheduled_call);
+
+			var runtime_info = transport.responseXML.getElementsByTagName("runtime-info")[0];
+
+			if (runtime_info)
+				parse_runtime_info(runtime_info);
+
+			if (feedsSortByUnread())
+				resort_feedlist();
+
+			hideOrShowFeeds(getInitParam("hide_read_feeds") == 1);
+
+		} else {
+			notify_error("Error communicating with server.");
+		}
+
+	} catch (e) {
+		exception_error("handle_rpc_reply", e, transport);
+	}
+
+	return true;
+}
+