diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 08f2654d4d2..76533abf50c 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -172,6 +172,7 @@ module ts {
 
         function getExcludedSymbolFlags(flags: SymbolFlags): SymbolFlags {
             var result: SymbolFlags = 0;
+            if (flags & SymbolFlags.BlockScoped) result |= SymbolFlags.BlockScopedExcludes;
             if (flags & SymbolFlags.Variable) result |= SymbolFlags.VariableExcludes;
             if (flags & SymbolFlags.Property) result |= SymbolFlags.PropertyExcludes;
             if (flags & SymbolFlags.EnumMember) result |= SymbolFlags.EnumMemberExcludes;
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates2.errors.txt b/tests/baselines/reference/letDeclarations-scopes-duplicates2.errors.txt
new file mode 100644
index 00000000000..324385b406e
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates2.errors.txt
@@ -0,0 +1,11 @@
+tests/cases/compiler/file2.ts(1,5): error TS2300: Duplicate identifier 'var1'.
+
+
+==== tests/cases/compiler/file1.ts (0 errors) ====
+    
+    let var1 = 0;
+    
+==== tests/cases/compiler/file2.ts (1 errors) ====
+    let var1 = 0;
+        ~~~~
+!!! error TS2300: Duplicate identifier 'var1'.
\ No newline at end of file
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates2.js b/tests/baselines/reference/letDeclarations-scopes-duplicates2.js
new file mode 100644
index 00000000000..9b35bd81c76
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates2.js
@@ -0,0 +1,13 @@
+//// [tests/cases/compiler/letDeclarations-scopes-duplicates2.ts] ////
+
+//// [file1.ts]
+
+let var1 = 0;
+
+//// [file2.ts]
+let var1 = 0;
+
+//// [file1.js]
+let var1 = 0;
+//// [file2.js]
+let var1 = 0;
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates3.errors.txt b/tests/baselines/reference/letDeclarations-scopes-duplicates3.errors.txt
new file mode 100644
index 00000000000..a85ca8bad04
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates3.errors.txt
@@ -0,0 +1,11 @@
+tests/cases/compiler/file2.ts(1,7): error TS2300: Duplicate identifier 'var1'.
+
+
+==== tests/cases/compiler/file1.ts (0 errors) ====
+    
+    let var1 = 0;
+    
+==== tests/cases/compiler/file2.ts (1 errors) ====
+    const var1 = 0;
+          ~~~~
+!!! error TS2300: Duplicate identifier 'var1'.
\ No newline at end of file
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates3.js b/tests/baselines/reference/letDeclarations-scopes-duplicates3.js
new file mode 100644
index 00000000000..e74caf37219
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates3.js
@@ -0,0 +1,13 @@
+//// [tests/cases/compiler/letDeclarations-scopes-duplicates3.ts] ////
+
+//// [file1.ts]
+
+let var1 = 0;
+
+//// [file2.ts]
+const var1 = 0;
+
+//// [file1.js]
+let var1 = 0;
+//// [file2.js]
+const var1 = 0;
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates4.errors.txt b/tests/baselines/reference/letDeclarations-scopes-duplicates4.errors.txt
new file mode 100644
index 00000000000..1a43932040f
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates4.errors.txt
@@ -0,0 +1,11 @@
+tests/cases/compiler/file2.ts(1,5): error TS2300: Duplicate identifier 'var1'.
+
+
+==== tests/cases/compiler/file1.ts (0 errors) ====
+    
+    const var1 = 0;
+    
+==== tests/cases/compiler/file2.ts (1 errors) ====
+    let var1 = 0;
+        ~~~~
+!!! error TS2300: Duplicate identifier 'var1'.
\ No newline at end of file
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates4.js b/tests/baselines/reference/letDeclarations-scopes-duplicates4.js
new file mode 100644
index 00000000000..ac338e31c72
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates4.js
@@ -0,0 +1,13 @@
+//// [tests/cases/compiler/letDeclarations-scopes-duplicates4.ts] ////
+
+//// [file1.ts]
+
+const var1 = 0;
+
+//// [file2.ts]
+let var1 = 0;
+
+//// [file1.js]
+const var1 = 0;
+//// [file2.js]
+let var1 = 0;
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates5.errors.txt b/tests/baselines/reference/letDeclarations-scopes-duplicates5.errors.txt
new file mode 100644
index 00000000000..49737b17740
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates5.errors.txt
@@ -0,0 +1,11 @@
+tests/cases/compiler/file2.ts(1,7): error TS2300: Duplicate identifier 'var1'.
+
+
+==== tests/cases/compiler/file1.ts (0 errors) ====
+    
+    const var1 = 0;
+    
+==== tests/cases/compiler/file2.ts (1 errors) ====
+    const var1 = 0;
+          ~~~~
+!!! error TS2300: Duplicate identifier 'var1'.
\ No newline at end of file
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates5.js b/tests/baselines/reference/letDeclarations-scopes-duplicates5.js
new file mode 100644
index 00000000000..2424c91ab90
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates5.js
@@ -0,0 +1,13 @@
+//// [tests/cases/compiler/letDeclarations-scopes-duplicates5.ts] ////
+
+//// [file1.ts]
+
+const var1 = 0;
+
+//// [file2.ts]
+const var1 = 0;
+
+//// [file1.js]
+const var1 = 0;
+//// [file2.js]
+const var1 = 0;
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates6.errors.txt b/tests/baselines/reference/letDeclarations-scopes-duplicates6.errors.txt
new file mode 100644
index 00000000000..2904227c8f8
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates6.errors.txt
@@ -0,0 +1,11 @@
+tests/cases/compiler/file2.ts(1,5): error TS2300: Duplicate identifier 'var1'.
+
+
+==== tests/cases/compiler/file1.ts (0 errors) ====
+    
+    var var1 = 0;
+    
+==== tests/cases/compiler/file2.ts (1 errors) ====
+    let var1 = 0;
+        ~~~~
+!!! error TS2300: Duplicate identifier 'var1'.
\ No newline at end of file
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates6.js b/tests/baselines/reference/letDeclarations-scopes-duplicates6.js
new file mode 100644
index 00000000000..24edc0b7bde
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates6.js
@@ -0,0 +1,13 @@
+//// [tests/cases/compiler/letDeclarations-scopes-duplicates6.ts] ////
+
+//// [file1.ts]
+
+var var1 = 0;
+
+//// [file2.ts]
+let var1 = 0;
+
+//// [file1.js]
+var var1 = 0;
+//// [file2.js]
+let var1 = 0;
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates7.errors.txt b/tests/baselines/reference/letDeclarations-scopes-duplicates7.errors.txt
new file mode 100644
index 00000000000..8dd0418b602
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates7.errors.txt
@@ -0,0 +1,11 @@
+tests/cases/compiler/file2.ts(1,5): error TS2300: Duplicate identifier 'var1'.
+
+
+==== tests/cases/compiler/file1.ts (0 errors) ====
+    
+    let var1 = 0;
+    
+==== tests/cases/compiler/file2.ts (1 errors) ====
+    var var1 = 0;
+        ~~~~
+!!! error TS2300: Duplicate identifier 'var1'.
\ No newline at end of file
diff --git a/tests/baselines/reference/letDeclarations-scopes-duplicates7.js b/tests/baselines/reference/letDeclarations-scopes-duplicates7.js
new file mode 100644
index 00000000000..4cbc359e2c2
--- /dev/null
+++ b/tests/baselines/reference/letDeclarations-scopes-duplicates7.js
@@ -0,0 +1,13 @@
+//// [tests/cases/compiler/letDeclarations-scopes-duplicates7.ts] ////
+
+//// [file1.ts]
+
+let var1 = 0;
+
+//// [file2.ts]
+var var1 = 0;
+
+//// [file1.js]
+let var1 = 0;
+//// [file2.js]
+var var1 = 0;
diff --git a/tests/cases/compiler/letDeclarations-scopes-duplicates2.ts b/tests/cases/compiler/letDeclarations-scopes-duplicates2.ts
new file mode 100644
index 00000000000..40ddc14fc3f
--- /dev/null
+++ b/tests/cases/compiler/letDeclarations-scopes-duplicates2.ts
@@ -0,0 +1,7 @@
+// @target: ES6
+
+// @Filename: file1.ts
+let var1 = 0;
+
+// @Filename: file2.ts
+let var1 = 0;
\ No newline at end of file
diff --git a/tests/cases/compiler/letDeclarations-scopes-duplicates3.ts b/tests/cases/compiler/letDeclarations-scopes-duplicates3.ts
new file mode 100644
index 00000000000..1f10efa5385
--- /dev/null
+++ b/tests/cases/compiler/letDeclarations-scopes-duplicates3.ts
@@ -0,0 +1,7 @@
+// @target: ES6
+
+// @Filename: file1.ts
+let var1 = 0;
+
+// @Filename: file2.ts
+const var1 = 0;
\ No newline at end of file
diff --git a/tests/cases/compiler/letDeclarations-scopes-duplicates4.ts b/tests/cases/compiler/letDeclarations-scopes-duplicates4.ts
new file mode 100644
index 00000000000..150d434a2bc
--- /dev/null
+++ b/tests/cases/compiler/letDeclarations-scopes-duplicates4.ts
@@ -0,0 +1,7 @@
+// @target: ES6
+
+// @Filename: file1.ts
+const var1 = 0;
+
+// @Filename: file2.ts
+let var1 = 0;
\ No newline at end of file
diff --git a/tests/cases/compiler/letDeclarations-scopes-duplicates5.ts b/tests/cases/compiler/letDeclarations-scopes-duplicates5.ts
new file mode 100644
index 00000000000..da249853499
--- /dev/null
+++ b/tests/cases/compiler/letDeclarations-scopes-duplicates5.ts
@@ -0,0 +1,7 @@
+// @target: ES6
+
+// @Filename: file1.ts
+const var1 = 0;
+
+// @Filename: file2.ts
+const var1 = 0;
\ No newline at end of file
diff --git a/tests/cases/compiler/letDeclarations-scopes-duplicates6.ts b/tests/cases/compiler/letDeclarations-scopes-duplicates6.ts
new file mode 100644
index 00000000000..f71b7623790
--- /dev/null
+++ b/tests/cases/compiler/letDeclarations-scopes-duplicates6.ts
@@ -0,0 +1,7 @@
+// @target: ES6
+
+// @Filename: file1.ts
+var var1 = 0;
+
+// @Filename: file2.ts
+let var1 = 0;
\ No newline at end of file
diff --git a/tests/cases/compiler/letDeclarations-scopes-duplicates7.ts b/tests/cases/compiler/letDeclarations-scopes-duplicates7.ts
new file mode 100644
index 00000000000..829fda0c927
--- /dev/null
+++ b/tests/cases/compiler/letDeclarations-scopes-duplicates7.ts
@@ -0,0 +1,7 @@
+// @target: ES6
+
+// @Filename: file1.ts
+let var1 = 0;
+
+// @Filename: file2.ts
+var var1 = 0;
\ No newline at end of file