diff --git a/src/harness/fourslash.ts b/src/harness/fourslash.ts
index ba7a5f20daecd..2fba2d132992d 100644
--- a/src/harness/fourslash.ts
+++ b/src/harness/fourslash.ts
@@ -1414,7 +1414,7 @@ namespace FourSlash {
                 return;
             }
 
-            const incrementalSourceFile = this.languageService.getSourceFile(this.activeFile.fileName);
+            const incrementalSourceFile = this.languageService.getNonBoundSourceFile(this.activeFile.fileName);
             Utils.assertInvariants(incrementalSourceFile, /*parent:*/ undefined);
 
             const incrementalSyntaxDiagnostics = incrementalSourceFile.parseDiagnostics;
diff --git a/src/harness/harnessLanguageService.ts b/src/harness/harnessLanguageService.ts
index 2a6ed85f9cd5d..12bb6a470e4f7 100644
--- a/src/harness/harnessLanguageService.ts
+++ b/src/harness/harnessLanguageService.ts
@@ -423,7 +423,7 @@ namespace Harness.LanguageService {
         getProgram(): ts.Program {
             throw new Error("Program can not be marshaled across the shim layer.");
         }
-        getSourceFile(fileName: string): ts.SourceFile {
+        getNonBoundSourceFile(fileName: string): ts.SourceFile {
             throw new Error("SourceFile can not be marshaled across the shim layer.");
         }
         dispose(): void { this.shim.dispose({}); }
diff --git a/src/server/client.ts b/src/server/client.ts
index 8731c52cc72fc..957d36e4a3ab1 100644
--- a/src/server/client.ts
+++ b/src/server/client.ts
@@ -613,7 +613,7 @@ namespace ts.server {
             throw new Error("SourceFile objects are not serializable through the server protocol.");
         }
 
-        getSourceFile(fileName: string): SourceFile {
+        getNonBoundSourceFile(fileName: string): SourceFile {
             throw new Error("SourceFile objects are not serializable through the server protocol.");
         }
 
diff --git a/src/server/editorServices.ts b/src/server/editorServices.ts
index 42a2bded6a51e..4a299ef6fd418 100644
--- a/src/server/editorServices.ts
+++ b/src/server/editorServices.ts
@@ -1330,7 +1330,7 @@ namespace ts.server {
         }
 
         isExternalModule(filename: string): boolean {
-            const sourceFile = this.languageService.getSourceFile(filename);
+            const sourceFile = this.languageService.getNonBoundSourceFile(filename);
             return ts.isExternalModule(sourceFile);
         }
 
diff --git a/src/services/services.ts b/src/services/services.ts
index 72255b554799d..a634b2baf1a49 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1112,7 +1112,7 @@ namespace ts {
 
         getProgram(): Program;
 
-        getSourceFile(fileName: string): SourceFile;
+        /* @internal */ getNonBoundSourceFile(fileName: string): SourceFile;
 
         dispose(): void;
     }
@@ -6528,7 +6528,7 @@ namespace ts {
         }
 
         /// Syntactic features
-        function getSourceFile(fileName: string): SourceFile {
+        function getNonBoundSourceFile(fileName: string): SourceFile {
             return syntaxTreeCache.getCurrentSourceFile(fileName);
         }
 
@@ -7616,7 +7616,7 @@ namespace ts {
             getFormattingEditsAfterKeystroke,
             getDocCommentTemplateAtPosition,
             getEmitOutput,
-            getSourceFile,
+            getNonBoundSourceFile,
             getProgram
         };
     }