diff --git a/src/scan/lexer.ts b/src/scan/lexer.ts
index 7b2adb70a..5a5e68cc6 100644
--- a/src/scan/lexer.ts
+++ b/src/scan/lexer.ts
@@ -51,7 +51,7 @@ namespace chevrotain {
             let longerAltClass = clazz.LONGER_ALT
 
             if (longerAltClass) {
-                let longerAltIdx = _.indexOf(onlyRelevantClasses, longerAltClass)
+                let longerAltIdx = utils.indexOf(onlyRelevantClasses, longerAltClass)
                 return longerAltIdx
             }
         })
diff --git a/src/utils/utils.ts b/src/utils/utils.ts
index 493ed81fc..acd2c6dd6 100644
--- a/src/utils/utils.ts
+++ b/src/utils/utils.ts
@@ -233,4 +233,13 @@ namespace chevrotain.utils {
         }
         return false
     }
+
+    export function indexOf<T>(arr:T[], value:T):number {
+        for (let i = 0; i < arr.length; i++) {
+            if (arr[i] === value) {
+                return i
+            }
+        }
+        return -1
+    }
 }
diff --git a/test/utils/utils_spec.ts b/test/utils/utils_spec.ts
index 2ab1fa198..2fdff7d37 100644
--- a/test/utils/utils_spec.ts
+++ b/test/utils/utils_spec.ts
@@ -155,6 +155,12 @@ namespace chevrotain.utils.spec {
             expect(some([1, 2, 3], (item) => {return item % 2 === 0})).to.be.true
             expect(some([1, 3, 5], (item) => {return item % 2 === 0})).to.be.false
         })
+
+        it("exports an indexOf utility", () => {
+            expect(indexOf([1, 2, 3], 2)).to.equal(1)
+            expect(indexOf([1, 2, 3], 3)).to.equal(2)
+            expect(indexOf([1, 2, 3], 0)).to.equal(-1)
+            expect(indexOf([], -2)).to.equal(-1)
+        })
     })
 }
-