diff --git a/tests/baselines/reference/fatarrowfunctionsOptionalArgsErrors1.errors.txt b/tests/baselines/reference/fatarrowfunctionsOptionalArgsErrors1.errors.txt
index 5934ab52ccf..b32a7b67b61 100644
--- a/tests/baselines/reference/fatarrowfunctionsOptionalArgsErrors1.errors.txt
+++ b/tests/baselines/reference/fatarrowfunctionsOptionalArgsErrors1.errors.txt
@@ -1,10 +1,9 @@
 tests/cases/compiler/fatarrowfunctionsOptionalArgsErrors1.ts(1,9): error TS1016: A required parameter cannot follow an optional parameter.
 tests/cases/compiler/fatarrowfunctionsOptionalArgsErrors1.ts(2,8): error TS1047: A rest parameter cannot be optional.
 tests/cases/compiler/fatarrowfunctionsOptionalArgsErrors1.ts(4,5): error TS1048: A rest parameter cannot have an initializer.
-tests/cases/compiler/fatarrowfunctionsOptionalArgsErrors1.ts(7,12): error TS1016: A required parameter cannot follow an optional parameter.
 
 
-==== tests/cases/compiler/fatarrowfunctionsOptionalArgsErrors1.ts (4 errors) ====
+==== tests/cases/compiler/fatarrowfunctionsOptionalArgsErrors1.ts (3 errors) ====
     (arg1?, arg2) => 101;
             ~~~~
 !!! error TS1016: A required parameter cannot follow an optional parameter.
@@ -16,7 +15,5 @@ tests/cases/compiler/fatarrowfunctionsOptionalArgsErrors1.ts(7,12): error TS1016
         ~~~
 !!! error TS1048: A rest parameter cannot have an initializer.
     
-    // Non optional parameter following an optional one
-    (arg1 = 1, arg2) => 1; 
-               ~~~~
-!!! error TS1016: A required parameter cannot follow an optional parameter.
\ No newline at end of file
+    // Uninitialized parameter makes the initialized one required
+    (arg1 = 1, arg2) => 1; 
\ No newline at end of file
diff --git a/tests/baselines/reference/fatarrowfunctionsOptionalArgsErrors1.js b/tests/baselines/reference/fatarrowfunctionsOptionalArgsErrors1.js
index e746b24a066..4d27f8230eb 100644
--- a/tests/baselines/reference/fatarrowfunctionsOptionalArgsErrors1.js
+++ b/tests/baselines/reference/fatarrowfunctionsOptionalArgsErrors1.js
@@ -4,7 +4,7 @@
 (...arg) => 103;
 (...arg:number [] = []) => 104;
 
-// Non optional parameter following an optional one
+// Uninitialized parameter makes the initialized one required
 (arg1 = 1, arg2) => 1; 
 
 //// [fatarrowfunctionsOptionalArgsErrors1.js]
@@ -30,7 +30,7 @@
     }
     return 104;
 });
-// Non optional parameter following an optional one
+// Uninitialized parameter makes the initialized one required
 (function (arg1, arg2) {
     if (arg1 === void 0) { arg1 = 1; }
     return 1;
diff --git a/tests/baselines/reference/optionalParamArgsTest.errors.txt b/tests/baselines/reference/optionalParamArgsTest.errors.txt
index 3c4d2e37be9..05fefa85065 100644
--- a/tests/baselines/reference/optionalParamArgsTest.errors.txt
+++ b/tests/baselines/reference/optionalParamArgsTest.errors.txt
@@ -1,6 +1,6 @@
 tests/cases/compiler/optionalParamArgsTest.ts(31,12): error TS2393: Duplicate function implementation.
-tests/cases/compiler/optionalParamArgsTest.ts(35,12): error TS2393: Duplicate function implementation.
-tests/cases/compiler/optionalParamArgsTest.ts(35,47): error TS1016: A required parameter cannot follow an optional parameter.
+tests/cases/compiler/optionalParamArgsTest.ts(34,12): error TS2393: Duplicate function implementation.
+tests/cases/compiler/optionalParamArgsTest.ts(98,1): error TS2346: Supplied parameters do not match any signature of call target.
 tests/cases/compiler/optionalParamArgsTest.ts(99,1): error TS2346: Supplied parameters do not match any signature of call target.
 tests/cases/compiler/optionalParamArgsTest.ts(100,1): error TS2346: Supplied parameters do not match any signature of call target.
 tests/cases/compiler/optionalParamArgsTest.ts(101,1): error TS2346: Supplied parameters do not match any signature of call target.
@@ -20,10 +20,9 @@ tests/cases/compiler/optionalParamArgsTest.ts(114,1): error TS2346: Supplied par
 tests/cases/compiler/optionalParamArgsTest.ts(115,1): error TS2346: Supplied parameters do not match any signature of call target.
 tests/cases/compiler/optionalParamArgsTest.ts(116,1): error TS2346: Supplied parameters do not match any signature of call target.
 tests/cases/compiler/optionalParamArgsTest.ts(117,1): error TS2346: Supplied parameters do not match any signature of call target.
-tests/cases/compiler/optionalParamArgsTest.ts(118,1): error TS2346: Supplied parameters do not match any signature of call target.
 
 
-==== tests/cases/compiler/optionalParamArgsTest.ts (23 errors) ====
+==== tests/cases/compiler/optionalParamArgsTest.ts (22 errors) ====
     // Optional parameter and default argument tests
     
     // Key:
@@ -58,13 +57,10 @@ tests/cases/compiler/optionalParamArgsTest.ts(118,1): error TS2346: Supplied par
                ~~~~
 !!! error TS2393: Duplicate function implementation.
     
-        // Negative test
-        // "Optional parameters may only be followed by other optional parameters"
+        // Uninitialized parameter makes the initialized one required
         public C1M5(C1M5A1:number,C1M5A2:number=0,C1M5A3:number) { return C1M5A1 + C1M5A2; }
                ~~~~
 !!! error TS2393: Duplicate function implementation.
-                                                  ~~~~~~
-!!! error TS1016: A required parameter cannot follow an optional parameter.
     }
     
     class C2 extends C1 {
diff --git a/tests/baselines/reference/optionalParamArgsTest.js b/tests/baselines/reference/optionalParamArgsTest.js
index 414f474598d..0c5a5d82814 100644
--- a/tests/baselines/reference/optionalParamArgsTest.js
+++ b/tests/baselines/reference/optionalParamArgsTest.js
@@ -31,8 +31,7 @@ class C1 {
 
     public C1M5(C1M5A1:number,C1M5A2:number=0,C1M5A3?:number) { return C1M5A1 + C1M5A2; }
 
-    // Negative test
-    // "Optional parameters may only be followed by other optional parameters"
+    // Uninitialized parameter makes the initialized one required
     public C1M5(C1M5A1:number,C1M5A2:number=0,C1M5A3:number) { return C1M5A1 + C1M5A2; }
 }
 
@@ -152,8 +151,7 @@ var C1 = (function () {
         if (C1M5A2 === void 0) { C1M5A2 = 0; }
         return C1M5A1 + C1M5A2;
     };
-    // Negative test
-    // "Optional parameters may only be followed by other optional parameters"
+    // Uninitialized parameter makes the initialized one required
     C1.prototype.C1M5 = function (C1M5A1, C1M5A2, C1M5A3) {
         if (C1M5A2 === void 0) { C1M5A2 = 0; }
         return C1M5A1 + C1M5A2;
diff --git a/tests/cases/compiler/fatarrowfunctionsOptionalArgsErrors1.ts b/tests/cases/compiler/fatarrowfunctionsOptionalArgsErrors1.ts
index d8ddcf4bb8f..814f1b41619 100644
--- a/tests/cases/compiler/fatarrowfunctionsOptionalArgsErrors1.ts
+++ b/tests/cases/compiler/fatarrowfunctionsOptionalArgsErrors1.ts
@@ -3,5 +3,5 @@
 (...arg) => 103;
 (...arg:number [] = []) => 104;
 
-// Non optional parameter following an optional one
+// Uninitialized parameter makes the initialized one required
 (arg1 = 1, arg2) => 1; 
\ No newline at end of file
diff --git a/tests/cases/compiler/optionalParamArgsTest.ts b/tests/cases/compiler/optionalParamArgsTest.ts
index ce34acae869..609cbfe4734 100644
--- a/tests/cases/compiler/optionalParamArgsTest.ts
+++ b/tests/cases/compiler/optionalParamArgsTest.ts
@@ -30,8 +30,7 @@ class C1 {
 
     public C1M5(C1M5A1:number,C1M5A2:number=0,C1M5A3?:number) { return C1M5A1 + C1M5A2; }
 
-    // Negative test
-    // "Optional parameters may only be followed by other optional parameters"
+    // Uninitialized parameter makes the initialized one required
     public C1M5(C1M5A1:number,C1M5A2:number=0,C1M5A3:number) { return C1M5A1 + C1M5A2; }
 }