diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index aee66834a11..03305dd368d 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -894,7 +894,7 @@ namespace ts {
                     return;
                 }
 
-                const sourcePathComponents = getNormalizedPathComponents(sourceFile.fileName, currentDirectory);
+                const sourcePathComponents = getNormalizedPathComponents(getCanonicalFileName(sourceFile.fileName), currentDirectory);
                 sourcePathComponents.pop(); // The base file name is not part of the common directory path
 
                 if (!commonPathComponents) {
@@ -903,9 +903,8 @@ namespace ts {
                     return;
                 }
 
-                const caseSensitive = host.useCaseSensitiveFileNames();
                 for (let i = 0, n = Math.min(commonPathComponents.length, sourcePathComponents.length); i < n; i++) {
-                    if (caseSensitive ? commonPathComponents[i] !== sourcePathComponents[i] : commonPathComponents[i].toLocaleLowerCase() !== sourcePathComponents[i].toLocaleLowerCase()) {
+                    if (commonPathComponents[i] !== sourcePathComponents[i]) {
                         if (i === 0) {
                             // Failed to find any common path component
                             return true;