diff --git a/src/index.ts b/src/index.ts
index a0079bd24..976c1ca89 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1097,9 +1097,13 @@ export function createFromPreloadedConfig(
       };
 
       getTypeInfo = (code: string, fileName: string, position: number) => {
-        updateMemoryCache(code, fileName);
+        const normalizedFileName = normalizeSlashes(fileName);
+        updateMemoryCache(code, normalizedFileName);
 
-        const info = service.getQuickInfoAtPosition(fileName, position);
+        const info = service.getQuickInfoAtPosition(
+          normalizedFileName,
+          position
+        );
         const name = ts.displayPartsToString(info ? info.displayParts : []);
         const comment = ts.displayPartsToString(info ? info.documentation : []);
 
@@ -1283,9 +1287,10 @@ export function createFromPreloadedConfig(
       };
 
       getTypeInfo = (code: string, fileName: string, position: number) => {
-        updateMemoryCache(code, fileName);
+        const normalizedFileName = normalizeSlashes(fileName);
+        updateMemoryCache(code, normalizedFileName);
 
-        const sourceFile = builderProgram.getSourceFile(fileName);
+        const sourceFile = builderProgram.getSourceFile(normalizedFileName);
         if (!sourceFile)
           throw new TypeError(`Unable to read file: ${fileName}`);