diff --git a/dwarf-cs/dwarf.core/lang/Lexer.cs b/dwarf-cs/dwarf.core/lang/Lexer.cs
index 21b96ed..1fbfd74 100644
--- a/dwarf-cs/dwarf.core/lang/Lexer.cs
+++ b/dwarf-cs/dwarf.core/lang/Lexer.cs
@@ -107,6 +107,11 @@ internal class Matcher
         public Token Token { get; private set; }
         public bool Stop { get; private set; }
 
+        public int MatchedLen
+        {
+            get { return matched.Length; }
+        }
+
         public Matcher(ITokenRule rule)
         {
             this.rule = rule;
@@ -208,12 +213,14 @@ public IEnumerable<Token> Tokenize(string source)
 
                 if (matchers.All(m => m.Stop))
                 {
+                    int len = 0;
+
                     foreach (var matcher in matchers)
                     {
-                        if (matcher.Token != null)
+                        if (matcher.Token != null && matcher.MatchedLen > len)
                         {
                             token = matcher.Token;
-                            break;
+                            len = matcher.MatchedLen;
                         }
                     }
 
diff --git a/dwarf-cs/tests/LexerTests.cs b/dwarf-cs/tests/LexerTests.cs
index e89afe0..0f92235 100644
--- a/dwarf-cs/tests/LexerTests.cs
+++ b/dwarf-cs/tests/LexerTests.cs
@@ -49,6 +49,20 @@ public void IfThenElseTest()
             Assert.AreEqual(expected, actual);
         }
 
+        [Test]
+        public void AmbiguousIdentifiersTest()
+        {
+            var source = Multiline(
+                "if iff");
+
+            var lexer = new Lexer();
+            var actual = String.Join("", lexer.Tokenize(source));
+
+            const string expected = "if [iff] ";
+
+            Assert.AreEqual(expected, actual);
+        }
+
         [Test]
         public void ConstTest()
         {