diff --git a/src/core/completions/installers/zsh-installer.ts b/src/core/completions/installers/zsh-installer.ts
index 6a4493180f..bada131abc 100644
--- a/src/core/completions/installers/zsh-installer.ts
+++ b/src/core/completions/installers/zsh-installer.ts
@@ -166,27 +166,6 @@ export class ZshInstaller {
     }
   }
 
-  /**
-   * Check if fpath configuration is needed for a given directory
-   * Used to verify if Oh My Zsh (or other) completions directory is already in fpath
-   *
-   * @param completionsDir - Directory to check for in fpath
-   * @returns true if configuration is needed, false if directory is already referenced
-   */
-  private async needsFpathConfig(completionsDir: string): Promise<boolean> {
-    try {
-      const zshrcPath = this.getZshrcPath();
-      const content = await fs.readFile(zshrcPath, 'utf-8');
-
-      // Check if fpath already includes this directory
-      return !content.includes(completionsDir);
-    } catch (error) {
-      // If we can't read .zshrc, assume config is needed
-      console.debug(`Unable to read .zshrc to check fpath config: ${error instanceof Error ? error.message : String(error)}`);
-      return true;
-    }
-  }
-
   /**
    * Remove .zshrc configuration
    * Used during uninstallation
@@ -287,17 +266,10 @@ export class ZshInstaller {
       // Write the completion script
       await fs.writeFile(targetPath, completionScript, 'utf-8');
 
-      // Auto-configure .zshrc
+      // Auto-configure .zshrc for standard Zsh only.
+      // Oh My Zsh loads custom/completions and runs compinit itself.
       let zshrcConfigured = false;
-      if (isOhMyZsh) {
-        // For Oh My Zsh, verify that custom/completions is in fpath
-        // If not, add it to .zshrc
-        const needsConfig = await this.needsFpathConfig(targetDir);
-        if (needsConfig) {
-          zshrcConfigured = await this.configureZshrc(targetDir);
-        }
-      } else {
-        // Standard Zsh always needs .zshrc configuration
+      if (!isOhMyZsh) {
         zshrcConfigured = await this.configureZshrc(targetDir);
       }
 
diff --git a/test/core/completions/installers/zsh-installer.test.ts b/test/core/completions/installers/zsh-installer.test.ts
index a6827f4be0..67168ff163 100644
--- a/test/core/completions/installers/zsh-installer.test.ts
+++ b/test/core/completions/installers/zsh-installer.test.ts
@@ -167,6 +167,7 @@ describe('ZshInstaller', () => {
 
       const result = await installer.install(testScript);
 
+      expect(result.zshrcConfigured).toBe(false);
       expect(result.instructions).toBeDefined();
       expect(result.instructions!.length).toBeGreaterThan(0);
       // Should include guidance about verifying fpath for Oh My Zsh
@@ -630,28 +631,29 @@ describe('ZshInstaller', () => {
       expect(content).toContain('compinit');
     });
 
-    it('should configure .zshrc for Oh My Zsh when fpath is missing', async () => {
+    it('should not configure .zshrc for Oh My Zsh', async () => {
       const ohMyZshPath = path.join(testHomeDir, '.oh-my-zsh');
       await fs.mkdir(ohMyZshPath, { recursive: true });
+      const zshrcPath = path.join(testHomeDir, '.zshrc');
+      const originalZshrc = [
+        'export ZSH="$HOME/.oh-my-zsh"',
+        'source "$ZSH/oh-my-zsh.sh"',
+        '',
+      ].join('\n');
+      await fs.writeFile(zshrcPath, originalZshrc);
 
       const result = await installer.install(testScript);
 
       expect(result.success).toBe(true);
       expect(result.isOhMyZsh).toBe(true);
-      // Should configure .zshrc if fpath doesn't already include the directory
-      expect(result.zshrcConfigured).toBe(true);
-
-      // Verify .zshrc was created with fpath configuration
-      const zshrcPath = path.join(testHomeDir, '.zshrc');
-      const exists = await fs.access(zshrcPath).then(() => true).catch(() => false);
-      expect(exists).toBe(true);
+      expect(result.zshrcConfigured).toBe(false);
 
-      if (exists) {
-        const content = await fs.readFile(zshrcPath, 'utf-8');
-        expect(content).toContain('fpath=');
-        // Check for custom/completions or custom\completions (Windows path separator)
-        expect(content).toMatch(/custom[/\\]completions/);
-      }
+      const content = await fs.readFile(zshrcPath, 'utf-8');
+      expect(content).toBe(originalZshrc);
+      expect(content).not.toContain('# OPENSPEC:START');
+      expect(content).not.toContain('autoload -Uz compinit');
+      expect(content).not.toContain('compinit');
+      expect(result.instructions!.join('\n')).toContain('Oh My Zsh');
     });
 
     it('should not include manual instructions when .zshrc was auto-configured', async () => {