diff --git a/packages/integrations/src/rewriteframes.ts b/packages/integrations/src/rewriteframes.ts
index afe084f50411..c0cb6a63239f 100644
--- a/packages/integrations/src/rewriteframes.ts
+++ b/packages/integrations/src/rewriteframes.ts
@@ -72,12 +72,12 @@ export class RewriteFrames implements Integration {
       return frame;
     }
     // Check if the frame filename begins with `/` or a Windows-style prefix such as `C:\`
-    const isWindowsFrame = /^[A-Z]:\\/.test(frame.filename);
+    const isWindowsFrame = /^[a-zA-Z]:\\/.test(frame.filename);
     const startsWithSlash = /^\//.test(frame.filename);
     if (isWindowsFrame || startsWithSlash) {
       const filename = isWindowsFrame
         ? frame.filename
-            .replace(/^[A-Z]:/, '') // remove Windows-style prefix
+            .replace(/^[a-zA-Z]:/, '') // remove Windows-style prefix
             .replace(/\\/g, '/') // replace all `\\` instances with `/`
         : frame.filename;
       const base = this._root ? relative(this._root, filename) : basename(filename);
diff --git a/packages/integrations/test/rewriteframes.test.ts b/packages/integrations/test/rewriteframes.test.ts
index b19e70143273..bdb794975938 100644
--- a/packages/integrations/test/rewriteframes.test.ts
+++ b/packages/integrations/test/rewriteframes.test.ts
@@ -6,6 +6,7 @@ let rewriteFrames: RewriteFrames;
 let exceptionEvent: Event;
 let exceptionWithoutStackTrace: Event;
 let windowsExceptionEvent: Event;
+let windowsLowerCaseExceptionEvent: Event;
 let multipleStacktracesEvent: Event;
 
 describe('RewriteFrames', () => {
@@ -32,6 +33,17 @@ describe('RewriteFrames', () => {
         ],
       },
     };
+    windowsLowerCaseExceptionEvent = {
+      exception: {
+        values: [
+          {
+            stacktrace: {
+              frames: [{ filename: 'c:\\www\\src\\app\\file1.js' }, { filename: 'c:\\www\\src\\app\\file2.js' }],
+            },
+          },
+        ],
+      },
+    };
     exceptionWithoutStackTrace = {
       exception: {
         values: [{}],
@@ -93,16 +105,22 @@ describe('RewriteFrames', () => {
     });
   });
 
-  describe('default iteratee appends basename to `app:///` if frame starts with `C:\\`', () => {
+  describe('default iteratee appends basename to `app:///` if frame starts with Windows path prefix', () => {
     beforeEach(() => {
       rewriteFrames = new RewriteFrames();
     });
 
-    it('transforms windowsExceptionEvent frames', () => {
+    it('transforms windowsExceptionEvent frames (C:\\)', () => {
       const event = rewriteFrames.process(windowsExceptionEvent);
       expect(event.exception!.values![0].stacktrace!.frames![0].filename).toEqual('app:///file1.js');
       expect(event.exception!.values![0].stacktrace!.frames![1].filename).toEqual('app:///file2.js');
     });
+
+    it('transforms windowsExceptionEvent frames with lower-case prefix (c:\\)', () => {
+      const event = rewriteFrames.process(windowsLowerCaseExceptionEvent);
+      expect(event.exception!.values![0].stacktrace!.frames![0].filename).toEqual('app:///file1.js');
+      expect(event.exception!.values![0].stacktrace!.frames![1].filename).toEqual('app:///file2.js');
+    });
   });
 
   describe('can use custom root to perform `relative` on filepaths', () => {
@@ -123,6 +141,12 @@ describe('RewriteFrames', () => {
       expect(event.exception!.values![0].stacktrace!.frames![0].filename).toEqual('app:///src/app/file1.js');
       expect(event.exception!.values![0].stacktrace!.frames![1].filename).toEqual('app:///src/app/file2.js');
     });
+
+    it('trasforms windowsExceptionEvent lower-case prefix frames', () => {
+      const event = rewriteFrames.process(windowsLowerCaseExceptionEvent);
+      expect(event.exception!.values![0].stacktrace!.frames![0].filename).toEqual('app:///src/app/file1.js');
+      expect(event.exception!.values![0].stacktrace!.frames![1].filename).toEqual('app:///src/app/file2.js');
+    });
   });
 
   describe('can use custom iteratee', () => {