diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 3b7e787fe4be3..9bd0d6475fe75 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -6605,7 +6605,7 @@ module ts {
                 result.splice(spliceIndex, 0, signature);
             }
         }
-
+
         function getSpreadArgumentIndex(args: Expression[]): number {
             for (let i = 0; i < args.length; i++) {
                 if (args[i].kind === SyntaxKind.SpreadElementExpression) {
@@ -10914,6 +10914,7 @@ module ts {
                     break;
                 case SyntaxKind.MethodDeclaration:
                 case SyntaxKind.MethodSignature:
+                    forEach(node.decorators, checkFunctionExpressionBodies);
                     forEach((<MethodDeclaration>node).parameters, checkFunctionExpressionBodies);
                     if (isObjectLiteralMethod(node)) {
                         checkFunctionExpressionOrObjectLiteralMethodBody(<MethodDeclaration>node);
@@ -10928,6 +10929,7 @@ module ts {
                 case SyntaxKind.WithStatement:
                     checkFunctionExpressionBodies((<WithStatement>node).expression);
                     break;
+                case SyntaxKind.Decorator:
                 case SyntaxKind.Parameter:
                 case SyntaxKind.PropertyDeclaration:
                 case SyntaxKind.PropertySignature:
diff --git a/tests/baselines/reference/decoratorChecksFunctionBodies.errors.txt b/tests/baselines/reference/decoratorChecksFunctionBodies.errors.txt
new file mode 100644
index 0000000000000..c8166b538fd5d
--- /dev/null
+++ b/tests/baselines/reference/decoratorChecksFunctionBodies.errors.txt
@@ -0,0 +1,21 @@
+tests/cases/conformance/decorators/class/decoratorChecksFunctionBodies.ts(9,14): error TS2345: Argument of type 'number' is not assignable to parameter of type 'string'.
+
+
+==== tests/cases/conformance/decorators/class/decoratorChecksFunctionBodies.ts (1 errors) ====
+    
+    // from #2971
+    function func(s: string): void {
+    }
+    
+    class A {
+        @(x => {
+            var a = 3;
+            func(a);
+                 ~
+!!! error TS2345: Argument of type 'number' is not assignable to parameter of type 'string'.
+            return x; 
+        })
+        m() {
+    
+        }
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/decoratorChecksFunctionBodies.js b/tests/baselines/reference/decoratorChecksFunctionBodies.js
new file mode 100644
index 0000000000000..020bc775aeaa0
--- /dev/null
+++ b/tests/baselines/reference/decoratorChecksFunctionBodies.js
@@ -0,0 +1,44 @@
+//// [decoratorChecksFunctionBodies.ts]
+
+// from #2971
+function func(s: string): void {
+}
+
+class A {
+    @(x => {
+        var a = 3;
+        func(a);
+        return x; 
+    })
+    m() {
+
+    }
+}
+
+//// [decoratorChecksFunctionBodies.js]
+var __decorate = (this && this.__decorate) || function (decorators, target, key, desc) {
+    if (typeof Reflect === "object" && typeof Reflect.decorate === "function") return Reflect.decorate(decorators, target, key, desc);
+    switch (arguments.length) {
+        case 2: return decorators.reduceRight(function(o, d) { return (d && d(o)) || o; }, target);
+        case 3: return decorators.reduceRight(function(o, d) { return (d && d(target, key)), void 0; }, void 0);
+        case 4: return decorators.reduceRight(function(o, d) { return (d && d(target, key, o)) || o; }, desc);
+    }
+};
+// from #2971
+function func(s) {
+}
+var A = (function () {
+    function A() {
+    }
+    A.prototype.m = function () {
+    };
+    Object.defineProperty(A.prototype, "m",
+        __decorate([
+            (function (x) {
+                var a = 3;
+                func(a);
+                return x;
+            })
+        ], A.prototype, "m", Object.getOwnPropertyDescriptor(A.prototype, "m")));
+    return A;
+})();
diff --git a/tests/baselines/reference/decoratorInstantiateModulesInFunctionBodies.js b/tests/baselines/reference/decoratorInstantiateModulesInFunctionBodies.js
new file mode 100644
index 0000000000000..313d77fa5ce0d
--- /dev/null
+++ b/tests/baselines/reference/decoratorInstantiateModulesInFunctionBodies.js
@@ -0,0 +1,53 @@
+//// [tests/cases/conformance/decorators/class/decoratorInstantiateModulesInFunctionBodies.ts] ////
+
+//// [a.ts]
+
+// from #3108
+export var test = 'abc';
+
+//// [b.ts]
+import { test } from './a';
+
+function filter(handler: any) {
+    return function (target: any) {
+        // ...
+    };
+}
+
+class Wat {
+    @filter(() => test == 'abc')
+    static whatever() {
+        // ...
+    }
+}
+
+//// [a.js]
+// from #3108
+exports.test = 'abc';
+//// [b.js]
+var __decorate = (this && this.__decorate) || function (decorators, target, key, desc) {
+    if (typeof Reflect === "object" && typeof Reflect.decorate === "function") return Reflect.decorate(decorators, target, key, desc);
+    switch (arguments.length) {
+        case 2: return decorators.reduceRight(function(o, d) { return (d && d(o)) || o; }, target);
+        case 3: return decorators.reduceRight(function(o, d) { return (d && d(target, key)), void 0; }, void 0);
+        case 4: return decorators.reduceRight(function(o, d) { return (d && d(target, key, o)) || o; }, desc);
+    }
+};
+var a_1 = require('./a');
+function filter(handler) {
+    return function (target) {
+        // ...
+    };
+}
+var Wat = (function () {
+    function Wat() {
+    }
+    Wat.whatever = function () {
+        // ...
+    };
+    Object.defineProperty(Wat, "whatever",
+        __decorate([
+            filter(function () { return a_1.test == 'abc'; })
+        ], Wat, "whatever", Object.getOwnPropertyDescriptor(Wat, "whatever")));
+    return Wat;
+})();
diff --git a/tests/baselines/reference/decoratorInstantiateModulesInFunctionBodies.symbols b/tests/baselines/reference/decoratorInstantiateModulesInFunctionBodies.symbols
new file mode 100644
index 0000000000000..5088e740a5736
--- /dev/null
+++ b/tests/baselines/reference/decoratorInstantiateModulesInFunctionBodies.symbols
@@ -0,0 +1,34 @@
+=== tests/cases/conformance/decorators/class/a.ts ===
+
+// from #3108
+export var test = 'abc';
+>test : Symbol(test, Decl(a.ts, 2, 10))
+
+=== tests/cases/conformance/decorators/class/b.ts ===
+import { test } from './a';
+>test : Symbol(test, Decl(b.ts, 0, 8))
+
+function filter(handler: any) {
+>filter : Symbol(filter, Decl(b.ts, 0, 27))
+>handler : Symbol(handler, Decl(b.ts, 2, 16))
+
+    return function (target: any) {
+>target : Symbol(target, Decl(b.ts, 3, 21))
+
+        // ...
+    };
+}
+
+class Wat {
+>Wat : Symbol(Wat, Decl(b.ts, 6, 1))
+
+    @filter(() => test == 'abc')
+>filter : Symbol(filter, Decl(b.ts, 0, 27))
+>test : Symbol(test, Decl(b.ts, 0, 8))
+
+    static whatever() {
+>whatever : Symbol(Wat.whatever, Decl(b.ts, 8, 11))
+
+        // ...
+    }
+}
diff --git a/tests/baselines/reference/decoratorInstantiateModulesInFunctionBodies.types b/tests/baselines/reference/decoratorInstantiateModulesInFunctionBodies.types
new file mode 100644
index 0000000000000..18d993af9bbf1
--- /dev/null
+++ b/tests/baselines/reference/decoratorInstantiateModulesInFunctionBodies.types
@@ -0,0 +1,40 @@
+=== tests/cases/conformance/decorators/class/a.ts ===
+
+// from #3108
+export var test = 'abc';
+>test : string
+>'abc' : string
+
+=== tests/cases/conformance/decorators/class/b.ts ===
+import { test } from './a';
+>test : string
+
+function filter(handler: any) {
+>filter : (handler: any) => (target: any) => void
+>handler : any
+
+    return function (target: any) {
+>function (target: any) {        // ...    } : (target: any) => void
+>target : any
+
+        // ...
+    };
+}
+
+class Wat {
+>Wat : Wat
+
+    @filter(() => test == 'abc')
+>filter(() => test == 'abc') : (target: any) => void
+>filter : (handler: any) => (target: any) => void
+>() => test == 'abc' : () => boolean
+>test == 'abc' : boolean
+>test : string
+>'abc' : string
+
+    static whatever() {
+>whatever : () => void
+
+        // ...
+    }
+}
diff --git a/tests/cases/conformance/decorators/class/decoratorChecksFunctionBodies.ts b/tests/cases/conformance/decorators/class/decoratorChecksFunctionBodies.ts
new file mode 100644
index 0000000000000..31f5fe8255116
--- /dev/null
+++ b/tests/cases/conformance/decorators/class/decoratorChecksFunctionBodies.ts
@@ -0,0 +1,16 @@
+// @target:es5
+
+// from #2971
+function func(s: string): void {
+}
+
+class A {
+    @(x => {
+        var a = 3;
+        func(a);
+        return x; 
+    })
+    m() {
+
+    }
+}
\ No newline at end of file
diff --git a/tests/cases/conformance/decorators/class/decoratorInstantiateModulesInFunctionBodies.ts b/tests/cases/conformance/decorators/class/decoratorInstantiateModulesInFunctionBodies.ts
new file mode 100644
index 0000000000000..7fa7ab8dd84cf
--- /dev/null
+++ b/tests/cases/conformance/decorators/class/decoratorInstantiateModulesInFunctionBodies.ts
@@ -0,0 +1,22 @@
+// @target:es5
+// @module:commonjs
+// @filename: a.ts
+
+// from #3108
+export var test = 'abc';
+
+// @filename: b.ts
+import { test } from './a';
+
+function filter(handler: any) {
+    return function (target: any) {
+        // ...
+    };
+}
+
+class Wat {
+    @filter(() => test == 'abc')
+    static whatever() {
+        // ...
+    }
+}
\ No newline at end of file