diff --git a/scripts/ior.ts b/scripts/ior.ts
index 91580203350..374747d8439 100644
--- a/scripts/ior.ts
+++ b/scripts/ior.ts
@@ -64,7 +64,6 @@ module Commands {
             }
             if (path.charAt(1) === ":") {
                 if (path.charAt(2) === directorySeparator) return 3;
-                return 2;
             }
             return 0;
         }
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 23493b3087d..157a0c7fd1d 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -1574,7 +1574,6 @@ namespace ts {
         }
         if (path.charCodeAt(1) === CharacterCodes.colon) {
             if (path.charCodeAt(2) === CharacterCodes.slash) return 3;
-            return 2;
         }
         // Per RFC 1738 'file' URI schema has the shape file://<host>/<path>
         // if <host> is omitted then it is assumed that host value is 'localhost',
diff --git a/tests/baselines/reference/declarationEmitRelativeModuleError.errors.txt b/tests/baselines/reference/declarationEmitRelativeModuleError.errors.txt
new file mode 100644
index 00000000000..32aea83b5e4
--- /dev/null
+++ b/tests/baselines/reference/declarationEmitRelativeModuleError.errors.txt
@@ -0,0 +1,13 @@
+tests/cases/compiler/declarationEmitRelativeModuleError.ts(5,16): error TS2436: Ambient module declaration cannot specify relative module name.
+
+
+==== tests/cases/compiler/declarationEmitRelativeModuleError.ts (1 errors) ====
+    declare module "b:block" { // <-- no error anymore
+        
+    }
+    
+    declare module "b:/block" { // <-- still an error
+                   ~~~~~~~~~~
+!!! error TS2436: Ambient module declaration cannot specify relative module name.
+        
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/declarationEmitRelativeModuleError.js b/tests/baselines/reference/declarationEmitRelativeModuleError.js
new file mode 100644
index 00000000000..e1d78ba5c03
--- /dev/null
+++ b/tests/baselines/reference/declarationEmitRelativeModuleError.js
@@ -0,0 +1,10 @@
+//// [declarationEmitRelativeModuleError.ts]
+declare module "b:block" { // <-- no error anymore
+    
+}
+
+declare module "b:/block" { // <-- still an error
+    
+}
+
+//// [declarationEmitRelativeModuleError.js]
diff --git a/tests/baselines/reference/declarationEmitRelativeModuleError.symbols b/tests/baselines/reference/declarationEmitRelativeModuleError.symbols
new file mode 100644
index 00000000000..d07a145116a
--- /dev/null
+++ b/tests/baselines/reference/declarationEmitRelativeModuleError.symbols
@@ -0,0 +1,9 @@
+=== tests/cases/compiler/declarationEmitRelativeModuleError.ts ===
+declare module "b:block" { // <-- no error anymore
+No type information for this code.    
+No type information for this code.}
+No type information for this code.
+No type information for this code.declare module "b:/block" { // <-- still an error
+No type information for this code.    
+No type information for this code.}
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/declarationEmitRelativeModuleError.types b/tests/baselines/reference/declarationEmitRelativeModuleError.types
new file mode 100644
index 00000000000..d07a145116a
--- /dev/null
+++ b/tests/baselines/reference/declarationEmitRelativeModuleError.types
@@ -0,0 +1,9 @@
+=== tests/cases/compiler/declarationEmitRelativeModuleError.ts ===
+declare module "b:block" { // <-- no error anymore
+No type information for this code.    
+No type information for this code.}
+No type information for this code.
+No type information for this code.declare module "b:/block" { // <-- still an error
+No type information for this code.    
+No type information for this code.}
+No type information for this code.
\ No newline at end of file
diff --git a/tests/cases/compiler/declarationEmitRelativeModuleError.ts b/tests/cases/compiler/declarationEmitRelativeModuleError.ts
new file mode 100644
index 00000000000..f358e81da43
--- /dev/null
+++ b/tests/cases/compiler/declarationEmitRelativeModuleError.ts
@@ -0,0 +1,7 @@
+declare module "b:block" { // <-- no error anymore
+    
+}
+
+declare module "b:/block" { // <-- still an error
+    
+}
\ No newline at end of file
diff --git a/tests/webTestServer.ts b/tests/webTestServer.ts
index 5a3b4cc5048..aff2ba0752a 100644
--- a/tests/webTestServer.ts
+++ b/tests/webTestServer.ts
@@ -61,7 +61,6 @@ function getRootLength(path: string): number {
     }
     if (path.charAt(1) === ":") {
         if (path.charAt(2) === directorySeparator) return 3;
-        return 2;
     }
     // Per RFC 1738 'file' URI schema has the shape file://<host>/<path>
     // if <host> is omitted then it is assumed that host value is 'localhost',