diff --git a/lib/ace/editor.js b/lib/ace/editor.js
index 127ff164..96065e92 100644
--- a/lib/ace/editor.js
+++ b/lib/ace/editor.js
@@ -115,7 +115,8 @@ var Editor =function(renderer, session) {
     };
 
     this.setSession = function(session) {
-        if (this.session == session) return;
+        if (this.session == session)
+            return;
 
         if (this.session) {
             var oldSession = this.session;
diff --git a/lib/ace/mode/javascript_highlight_rules.js b/lib/ace/mode/javascript_highlight_rules.js
index 864c020f..e3f54c63 100644
--- a/lib/ace/mode/javascript_highlight_rules.js
+++ b/lib/ace/mode/javascript_highlight_rules.js
@@ -82,9 +82,6 @@ var JavaScriptHighlightRules = function() {
                 token : "comment", // multi line comment
                 regex : "\\/\\*",
                 next : "comment"
-            }, {
-                token : "string.regexp",
-                regex : "[/](?:(?:\\[(?:\\\\]|[^\\]])+\\])|(?:\\\\/|[^\\]/]))*[/]\\w*\\s*(?=[).,;]|$)"
             }, {
                 token : "string", // single line
                 regex : '["](?:(?:\\\\.)|(?:[^"\\\\]))*?["]'
@@ -126,13 +123,19 @@ var JavaScriptHighlightRules = function() {
                 regex : identifierRe
             }, {
                 token : "keyword.operator",
-                regex : "!|\\$|%|&|\\*|\\-\\-|\\-|\\+\\+|\\+|~|===|==|=|!=|!==|<=|>=|<<=|>>=|>>>=|<>|<|>|!|&&|\\|\\||\\?\\:|\\*=|%=|\\+=|\\-=|&=|\\^=|\\b(?:in|instanceof|new|delete|typeof|void)"
+                regex : "!|\\$|%|&|\\*|\\-\\-|\\-|\\+\\+|\\+|~|===|==|=|!=|!==|<=|>=|<<=|>>=|>>>=|<>|<|>|!|&&|\\|\\||\\?\\:|\\*=|%=|\\+=|\\-=|&=|\\^=|\\b(?:in|instanceof|new|delete|typeof|void)",
+                next  : "regex_allowed"
             }, {
                 token : "lparen",
-                regex : "[[({]"
+                regex : "[[({]",
+                next  : "regex_allowed"
             }, {
                 token : "rparen",
                 regex : "[\\])}]"
+            }, {
+                token : "keyword.operator",
+                regex : "\\/=?",
+                next  : "regex_allowed"
             }, {
                 token: "comment",
                 regex: "^#!.*$" 
@@ -141,6 +144,26 @@ var JavaScriptHighlightRules = function() {
                 regex : "\\s+"
             }
         ],
+        // regular expressions are only allowed after certain tokens. This
+        // makes sure we don't mix up regexps with the divison operator
+        "regex_allowed": [
+            {
+                token: "string.regexp",
+                regex: "\\/(?:(?:\\[(?:\\\\]|[^\\]])+\\])"
+                    + "|(?:\\\\/|[^\\]/]))*" 
+                    + "[/]\\w*",
+                next: "start"
+            }, {
+                token : "text",
+                regex : "\\s+"
+            }, {
+                // immediately return to the start mode without mathcing
+                // anything
+                token: "empty", 
+                regex: "",
+                next: "start"
+            }
+        ],
         "comment" : [
             {
                 token : "comment", // closing comment
diff --git a/lib/ace/mode/javascript_tokenizer_test.js b/lib/ace/mode/javascript_tokenizer_test.js
index cc630fc5..a7e5594a 100644
--- a/lib/ace/mode/javascript_tokenizer_test.js
+++ b/lib/ace/mode/javascript_tokenizer_test.js
@@ -96,19 +96,42 @@ module.exports = {
         assert.equal("text", tokens[1].type);
         assert.equal("rparen", tokens[2].type);
     },
-    
+
     "test for last rule in ruleset to catch capturing group bugs" : function() {
         var tokens = this.tokenizer.getLineTokens("}", "start").tokens;
-        
+
         assert.equal(1, tokens.length);
         assert.equal("rparen", tokens[0].type);
     },
-    
-    "test tokenize regular expressions": function() {
+
+    "test tokenize arithmetic expression which looks like a regexp": function() {
         var tokens = this.tokenizer.getLineTokens("a/b/c", "start").tokens;
         assert.equal(5, tokens.length);
+
+        var tokens = this.tokenizer.getLineTokens("a/=b/c", "start").tokens;
+        assert.equal(5, tokens.length);
+    },
+
+    "test tokenize reg exps" : function() {
+        var tokens = this.tokenizer.getLineTokens("a=/b/g", "start").tokens;
+        assert.equal(3, tokens.length);
+        assert.equal("string.regexp", tokens[2].type);
+        
+        var tokens = this.tokenizer.getLineTokens("a+/b/g", "start").tokens;
+        assert.equal(3, tokens.length);
+        assert.equal("string.regexp", tokens[2].type);
+        
+        var tokens = this.tokenizer.getLineTokens("a = 1 + /2 + 1/b", "start").tokens;
+        assert.equal(9, tokens.length);
+        assert.equal("string.regexp", tokens[8].type);
+
+        var tokens = this.tokenizer.getLineTokens("a=/a/ / /a/", "start").tokens;
+        assert.equal(7, tokens.length);
+        assert.equal("string.regexp", tokens[2].type);
+        assert.equal("string.regexp", tokens[6].type);
     },
     
+
     "test tokenize identifier with umlauts": function() {
         var tokens = this.tokenizer.getLineTokens("füße", "start").tokens;
         assert.equal(1, tokens.length);
diff --git a/lib/ace/tokenizer.js b/lib/ace/tokenizer.js
index 74234607..6e599da6 100644
--- a/lib/ace/tokenizer.js
+++ b/lib/ace/tokenizer.js
@@ -103,13 +103,15 @@ var Tokenizer = function(rules) {
                         value = match.slice(i+2, i+1+mapping[i].len);
                     }
                     
+                    // compute token type
                     if (typeof rule.token == "function")
                         type = rule.token.apply(this, value);
                     else
                         type = rule.token;
 
-                    if (rule.next && rule.next !== currentState) {
-                        currentState = rule.next;
+                    var next = rule.next;                    
+                    if (next && next !== currentState) {
+                        currentState = next;
                         state = this.rules[currentState];
                         mapping = this.matchMappings[currentState];
                         lastIndex = re.lastIndex;
@@ -120,26 +122,26 @@ var Tokenizer = function(rules) {
                     break;
                 }
             };
-            
-            if (typeof type == "string") {
-                if (typeof value != "string") {
+
+            if (value[0]) {
+                if (typeof type == "string") {
                     value = [value.join("")];
+                    type = [type];
                 }
-                type = [type];
-            }
             
-            for ( var i = 0; i < value.length; i++) {
-                if (token.type !== type[i]) {
-                    if (token.type) {
-                        tokens.push(token);
-                    }
+                for (var i = 0; i < value.length; i++) {
+                    if (token.type !== type[i]) {
+                        if (token.type) {
+                            tokens.push(token);
+                        }
                     
-                    token = {
-                        type: type[i],
-                        value: value[i]
+                        token = {
+                            type: type[i],
+                            value: value[i]
+                        }
+                    } else {
+                        token.value += value[i];
                     }
-                } else {
-                    token.value += value[i];
                 }
             }