diff --git a/src/core/prompts/__tests__/custom-system-prompt.spec.ts b/src/core/prompts/__tests__/custom-system-prompt.spec.ts
index b2ae067a3a..60984f95e0 100644
--- a/src/core/prompts/__tests__/custom-system-prompt.spec.ts
+++ b/src/core/prompts/__tests__/custom-system-prompt.spec.ts
@@ -39,11 +39,30 @@ vi.mock("../../../utils/fs", () => ({
 	createDirectoriesForFile: vi.fn().mockResolvedValue([]),
 }))
 
+vi.mock("../../../services/code-index/manager", () => ({
+	CodeIndexManager: {
+		getInstance: vi.fn().mockReturnValue({
+			isEnabled: false,
+			hasIndex: false,
+		}),
+	},
+}))
+
+vi.mock("os", () => ({
+	default: {
+		type: vi.fn().mockReturnValue("Windows_NT"),
+		homedir: vi.fn().mockReturnValue("/home/test"),
+	},
+	type: vi.fn().mockReturnValue("Windows_NT"),
+	homedir: vi.fn().mockReturnValue("/home/test"),
+}))
+
+// Import path module to add toPosix to String prototype
+import "../../../utils/path"
 import { SYSTEM_PROMPT } from "../system"
 import { defaultModeSlug, modes } from "../../../shared/modes"
 import * as vscode from "vscode"
 import * as fs from "fs/promises"
-import { toPosix } from "./utils"
 
 // Get the mocked fs module
 const mockedFs = vi.mocked(fs)
@@ -121,7 +140,11 @@ describe("File-Based Custom System Prompt", () => {
 		const fileCustomSystemPrompt = "Custom system prompt from file"
 		// When called with utf-8 encoding, return a string
 		mockedFs.readFile.mockImplementation((filePath, options) => {
-			if (toPosix(filePath).includes(`.roo/system-prompt-${defaultModeSlug}`) && options === "utf-8") {
+			// Convert filePath to string and normalize path separators
+			const normalizedPath =
+				typeof filePath === "string" ? filePath.replace(/\\/g, "/") : filePath.toString().replace(/\\/g, "/")
+
+			if (normalizedPath.includes(`.roo/system-prompt-${defaultModeSlug}`) && options === "utf-8") {
 				return Promise.resolve(fileCustomSystemPrompt)
 			}
 			return Promise.reject({ code: "ENOENT" })
@@ -159,7 +182,11 @@ describe("File-Based Custom System Prompt", () => {
 		// Mock the readFile to return content from a file
 		const fileCustomSystemPrompt = "Custom system prompt from file"
 		mockedFs.readFile.mockImplementation((filePath, options) => {
-			if (toPosix(filePath).includes(`.roo/system-prompt-${defaultModeSlug}`) && options === "utf-8") {
+			// Convert filePath to string and normalize path separators
+			const normalizedPath =
+				typeof filePath === "string" ? filePath.replace(/\\/g, "/") : filePath.toString().replace(/\\/g, "/")
+
+			if (normalizedPath.includes(`.roo/system-prompt-${defaultModeSlug}`) && options === "utf-8") {
 				return Promise.resolve(fileCustomSystemPrompt)
 			}
 			return Promise.reject({ code: "ENOENT" })
diff --git a/src/core/prompts/__tests__/responses-rooignore.spec.ts b/src/core/prompts/__tests__/responses-rooignore.spec.ts
index ca0dcfbad5..7428c0db6a 100644
--- a/src/core/prompts/__tests__/responses-rooignore.spec.ts
+++ b/src/core/prompts/__tests__/responses-rooignore.spec.ts
@@ -2,11 +2,12 @@
 
 import type { Mock } from "vitest"
 
+// Import path module to add toPosix to String prototype
+import "../../../utils/path"
 import { formatResponse } from "../responses"
 import { RooIgnoreController, LOCK_TEXT_SYMBOL } from "../../ignore/RooIgnoreController"
 import { fileExistsAtPath } from "../../../utils/fs"
 import * as fs from "fs/promises"
-import { toPosix } from "./utils"
 
 // Mock dependencies
 vi.mock("../../../utils/fs")
@@ -86,7 +87,7 @@ describe("RooIgnore Response Formatting", () => {
 				return (
 					!filePath.includes("node_modules") &&
 					!filePath.includes(".git") &&
-					!toPosix(filePath).includes("secrets/")
+					!filePath.toString().toPosix().includes("secrets/")
 				)
 			})
 
@@ -130,7 +131,7 @@ describe("RooIgnore Response Formatting", () => {
 				return (
 					!filePath.includes("node_modules") &&
 					!filePath.includes(".git") &&
-					!toPosix(filePath).includes("secrets/")
+					!filePath.toString().toPosix().includes("secrets/")
 				)
 			})
 
diff --git a/src/core/prompts/__tests__/utils.ts b/src/core/prompts/__tests__/utils.ts
deleted file mode 100644
index f2ac4fec1e..0000000000
--- a/src/core/prompts/__tests__/utils.ts
+++ /dev/null
@@ -1,7 +0,0 @@
-import * as fs from "fs/promises"
-import { PathLike } from "fs"
-
-// Make a path take a unix-like form.  Useful for making path comparisons.
-export function toPosix(filePath: PathLike | fs.FileHandle) {
-	return filePath.toString().toPosix()
-}