diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 6d21a9b5e3ffc..7f02258815192 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -17244,7 +17244,8 @@ namespace ts {
         }
 
         function checkGrammarForDisallowedTrailingComma(list: NodeArray<Node>): boolean {
-            if (list && list.hasTrailingComma) {
+            if (list && list.hasTrailingComma &&
+                !(list[0].parent.kind === SyntaxKind.FunctionDeclaration || list[0].parent.kind === SyntaxKind.ArrowFunction)) {
                 const start = list.end - ",".length;
                 const end = list.end;
                 const sourceFile = getSourceFileOfNode(list[0]);
diff --git a/tests/baselines/reference/ArrowFunction2.errors.txt b/tests/baselines/reference/ArrowFunction2.errors.txt
index 3b9ba21f15af9..c4685cacaca01 100644
--- a/tests/baselines/reference/ArrowFunction2.errors.txt
+++ b/tests/baselines/reference/ArrowFunction2.errors.txt
@@ -1,12 +1,9 @@
 tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ArrowFunctions/ArrowFunction2.ts(1,13): error TS2304: Cannot find name 'b'.
-tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ArrowFunctions/ArrowFunction2.ts(1,14): error TS1009: Trailing comma not allowed.
 
 
-==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ArrowFunctions/ArrowFunction2.ts (2 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ArrowFunctions/ArrowFunction2.ts (1 errors) ====
     var v = (a: b,) => {
                 ~
 !!! error TS2304: Cannot find name 'b'.
-                 ~
-!!! error TS1009: Trailing comma not allowed.
        
     };
\ No newline at end of file
diff --git a/tests/baselines/reference/parserErrorRecovery_ParameterList3.errors.txt b/tests/baselines/reference/parserErrorRecovery_ParameterList3.errors.txt
deleted file mode 100644
index df73dc51ce15a..0000000000000
--- a/tests/baselines/reference/parserErrorRecovery_ParameterList3.errors.txt
+++ /dev/null
@@ -1,8 +0,0 @@
-tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ParameterLists/parserErrorRecovery_ParameterList3.ts(1,13): error TS1009: Trailing comma not allowed.
-
-
-==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ParameterLists/parserErrorRecovery_ParameterList3.ts (1 errors) ====
-    function f(a,) {
-                ~
-!!! error TS1009: Trailing comma not allowed.
-    }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserErrorRecovery_ParameterList3.js b/tests/baselines/reference/parserErrorRecovery_ParameterList3.js
deleted file mode 100644
index 4c20e676f40ba..0000000000000
--- a/tests/baselines/reference/parserErrorRecovery_ParameterList3.js
+++ /dev/null
@@ -1,7 +0,0 @@
-//// [parserErrorRecovery_ParameterList3.ts]
-function f(a,) {
-}
-
-//// [parserErrorRecovery_ParameterList3.js]
-function f(a) {
-}
diff --git a/tests/baselines/reference/parserParameterList12.errors.txt b/tests/baselines/reference/parserParameterList12.errors.txt
deleted file mode 100644
index 686b29f63b18f..0000000000000
--- a/tests/baselines/reference/parserParameterList12.errors.txt
+++ /dev/null
@@ -1,8 +0,0 @@
-tests/cases/conformance/parser/ecmascript5/ParameterLists/parserParameterList12.ts(1,13): error TS1009: Trailing comma not allowed.
-
-
-==== tests/cases/conformance/parser/ecmascript5/ParameterLists/parserParameterList12.ts (1 errors) ====
-    function F(a,) {
-                ~
-!!! error TS1009: Trailing comma not allowed.
-    }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserParameterList12.symbols b/tests/baselines/reference/parserParameterList12.symbols
new file mode 100644
index 0000000000000..efaab7d1b13b1
--- /dev/null
+++ b/tests/baselines/reference/parserParameterList12.symbols
@@ -0,0 +1,5 @@
+=== tests/cases/conformance/parser/ecmascript5/ParameterLists/parserParameterList12.ts ===
+function F(a,) {
+>F : Symbol(F, Decl(parserParameterList12.ts, 0, 0))
+>a : Symbol(a, Decl(parserParameterList12.ts, 0, 11))
+}
diff --git a/tests/baselines/reference/parserParameterList12.types b/tests/baselines/reference/parserParameterList12.types
new file mode 100644
index 0000000000000..7ff43cd6a15c7
--- /dev/null
+++ b/tests/baselines/reference/parserParameterList12.types
@@ -0,0 +1,5 @@
+=== tests/cases/conformance/parser/ecmascript5/ParameterLists/parserParameterList12.ts ===
+function F(a,) {
+>F : (a: any) => void
+>a : any
+}
diff --git a/tests/baselines/reference/parserX_ArrowFunction2.errors.txt b/tests/baselines/reference/parserX_ArrowFunction2.errors.txt
index 20b4cb45e453c..f2195c4dc2fea 100644
--- a/tests/baselines/reference/parserX_ArrowFunction2.errors.txt
+++ b/tests/baselines/reference/parserX_ArrowFunction2.errors.txt
@@ -1,12 +1,9 @@
 tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ArrowFunctions/parserX_ArrowFunction2.ts(1,13): error TS2304: Cannot find name 'b'.
-tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ArrowFunctions/parserX_ArrowFunction2.ts(1,14): error TS1009: Trailing comma not allowed.
 
 
-==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ArrowFunctions/parserX_ArrowFunction2.ts (2 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ArrowFunctions/parserX_ArrowFunction2.ts (1 errors) ====
     var v = (a: b,) => {
                 ~
 !!! error TS2304: Cannot find name 'b'.
-                 ~
-!!! error TS1009: Trailing comma not allowed.
        
     };
\ No newline at end of file
diff --git a/tests/baselines/reference/trailingCommasInFunctionParameter.js b/tests/baselines/reference/trailingCommasInFunctionParameter.js
new file mode 100644
index 0000000000000..0aed2d31d2907
--- /dev/null
+++ b/tests/baselines/reference/trailingCommasInFunctionParameter.js
@@ -0,0 +1,14 @@
+//// [trailingCommasInFunctionParameter.ts]
+function f1(x, y,) {
+}
+
+function f2() {
+    return (x,) => {}
+}
+
+//// [trailingCommasInFunctionParameter.js]
+function f1(x, y) {
+}
+function f2() {
+    return function (x) { };
+}
diff --git a/tests/baselines/reference/trailingCommasInFunctionParameter.symbols b/tests/baselines/reference/trailingCommasInFunctionParameter.symbols
new file mode 100644
index 0000000000000..cd3257b46c52b
--- /dev/null
+++ b/tests/baselines/reference/trailingCommasInFunctionParameter.symbols
@@ -0,0 +1,13 @@
+=== tests/cases/conformance/es7/trailingCommasInFunctionParamLists/trailingCommasInFunctionParameter.ts ===
+function f1(x, y,) {
+>f1 : Symbol(f1, Decl(trailingCommasInFunctionParameter.ts, 0, 0))
+>x : Symbol(x, Decl(trailingCommasInFunctionParameter.ts, 0, 12))
+>y : Symbol(y, Decl(trailingCommasInFunctionParameter.ts, 0, 14))
+}
+
+function f2() {
+>f2 : Symbol(f2, Decl(trailingCommasInFunctionParameter.ts, 1, 1))
+
+    return (x,) => {}
+>x : Symbol(x, Decl(trailingCommasInFunctionParameter.ts, 4, 12))
+}
diff --git a/tests/baselines/reference/trailingCommasInFunctionParameter.types b/tests/baselines/reference/trailingCommasInFunctionParameter.types
new file mode 100644
index 0000000000000..cef7cf85f0229
--- /dev/null
+++ b/tests/baselines/reference/trailingCommasInFunctionParameter.types
@@ -0,0 +1,14 @@
+=== tests/cases/conformance/es7/trailingCommasInFunctionParamLists/trailingCommasInFunctionParameter.ts ===
+function f1(x, y,) {
+>f1 : (x: any, y: any) => void
+>x : any
+>y : any
+}
+
+function f2() {
+>f2 : () => (x: any) => void
+
+    return (x,) => {}
+>(x,) => {} : (x: any) => void
+>x : any
+}
diff --git a/tests/cases/conformance/es7/trailingCommasInFunctionParamLists/trailingCommasInFunctionParameter.ts b/tests/cases/conformance/es7/trailingCommasInFunctionParamLists/trailingCommasInFunctionParameter.ts
new file mode 100644
index 0000000000000..dbb911a9c288f
--- /dev/null
+++ b/tests/cases/conformance/es7/trailingCommasInFunctionParamLists/trailingCommasInFunctionParameter.ts
@@ -0,0 +1,7 @@
+// @target: es5
+function f1(x, y,) {
+}
+
+function f2() {
+    return (x,) => {}
+}
\ No newline at end of file
diff --git a/tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ParameterLists/parserErrorRecovery_ParameterList3.ts b/tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ParameterLists/parserErrorRecovery_ParameterList3.ts
deleted file mode 100644
index c51a52ef83ef2..0000000000000
--- a/tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ParameterLists/parserErrorRecovery_ParameterList3.ts
+++ /dev/null
@@ -1,2 +0,0 @@
-function f(a,) {
-}
\ No newline at end of file