diff --git a/packages/typescript/lib/node/decorateLanguageService.ts b/packages/typescript/lib/node/decorateLanguageService.ts
index 289efbdc..bb423810 100644
--- a/packages/typescript/lib/node/decorateLanguageService.ts
+++ b/packages/typescript/lib/node/decorateLanguageService.ts
@@ -458,17 +458,17 @@ export function decorateLanguageService(language: Language, languageService: ts.
 	};
 	languageService.getSyntacticDiagnostics = fileName => {
 		return getSyntacticDiagnostics(fileName)
-			.map(d => transformDiagnostic(language, d))
+			.map(d => transformDiagnostic(language, d, false))
 			.filter(notEmpty);
 	};
 	languageService.getSemanticDiagnostics = fileName => {
 		return getSemanticDiagnostics(fileName)
-			.map(d => transformDiagnostic(language, d))
+			.map(d => transformDiagnostic(language, d, false))
 			.filter(notEmpty);
 	};
 	languageService.getSuggestionDiagnostics = fileName => {
 		return getSuggestionDiagnostics(fileName)
-			.map(d => transformDiagnostic(language, d))
+			.map(d => transformDiagnostic(language, d, false))
 			.filter(notEmpty);
 	};
 	languageService.getDefinitionAndBoundSpan = (fileName, position) => {
diff --git a/packages/typescript/lib/node/decorateProgram.ts b/packages/typescript/lib/node/decorateProgram.ts
index d3d3eaa0..d7c303ec 100644
--- a/packages/typescript/lib/node/decorateProgram.ts
+++ b/packages/typescript/lib/node/decorateProgram.ts
@@ -22,29 +22,29 @@ export function decorateProgram(language: Language, program: ts.Program) {
 		return {
 			...result,
 			diagnostics: result.diagnostics
-				.map(d => transformDiagnostic(language, d))
+				.map(d => transformDiagnostic(language, d, true))
 				.filter(notEmpty),
 		};
 	};
 	program.getSyntacticDiagnostics = (sourceFile, cancellationToken) => {
 		return getSyntacticDiagnostics(sourceFile, cancellationToken)
-			.map(d => transformDiagnostic(language, d))
+			.map(d => transformDiagnostic(language, d, true))
 			.filter(notEmpty);
 	};
 	program.getSemanticDiagnostics = (sourceFile, cancellationToken) => {
 		return getSemanticDiagnostics(sourceFile, cancellationToken)
-			.map(d => transformDiagnostic(language, d))
+			.map(d => transformDiagnostic(language, d, true))
 			.filter(notEmpty);
 	};
 	program.getGlobalDiagnostics = cancellationToken => {
 		return getGlobalDiagnostics(cancellationToken)
-			.map(d => transformDiagnostic(language, d))
+			.map(d => transformDiagnostic(language, d, true))
 			.filter(notEmpty);
 	};
 	// @ts-ignore
 	program.getBindAndCheckDiagnostics = (sourceFile, cancellationToken) => {
 		return (getBindAndCheckDiagnostics as typeof getSyntacticDiagnostics)(sourceFile, cancellationToken)
-			.map(d => transformDiagnostic(language, d))
+			.map(d => transformDiagnostic(language, d, true))
 			.filter(notEmpty);
 	};
 
diff --git a/packages/typescript/lib/node/transform.ts b/packages/typescript/lib/node/transform.ts
index 514f69cc..4c2a13bb 100644
--- a/packages/typescript/lib/node/transform.ts
+++ b/packages/typescript/lib/node/transform.ts
@@ -15,14 +15,14 @@ export function transformCallHierarchyItem(language: Language, item: ts.CallHier
 	};
 }
 
-export function transformDiagnostic<T extends ts.Diagnostic>(language: Language, diagnostic: T): T | undefined {
+export function transformDiagnostic<T extends ts.Diagnostic>(language: Language, diagnostic: T, isTsc: boolean): T | undefined {
 	if (!transformedDiagnostics.has(diagnostic)) {
 		transformedDiagnostics.set(diagnostic, undefined);
 
 		const { relatedInformation } = diagnostic;
 		if (relatedInformation) {
 			diagnostic.relatedInformation = relatedInformation
-				.map(d => transformDiagnostic(language, d))
+				.map(d => transformDiagnostic(language, d, isTsc))
 				.filter(notEmpty);
 		}
 
@@ -35,7 +35,9 @@ export function transformDiagnostic<T extends ts.Diagnostic>(language: Language,
 			if (serviceScript) {
 				const sourceSpan = transformTextSpan(sourceScript, map, { start: diagnostic.start, length: diagnostic.length }, shouldReportDiagnostics);
 				if (sourceSpan) {
-					fillSourceFileText(language, diagnostic.file);
+					if (isTsc) {
+						fillSourceFileText(language, diagnostic.file);
+					}
 					transformedDiagnostics.set(diagnostic, {
 						...diagnostic,
 						start: sourceSpan.start,
@@ -65,7 +67,6 @@ export function fillSourceFileText(language: Language, sourceFile: ts.SourceFile
 		sourceFile.text = sourceScript.snapshot.getText(0, sourceScript.snapshot.getLength())
 			+ sourceFile.text.substring(sourceScript.snapshot.getLength());
 	}
-	return;
 }
 
 export function transformFileTextChanges(language: Language, changes: ts.FileTextChanges, filter: (data: CodeInformation) => boolean): ts.FileTextChanges | undefined {