diff --git a/apps/browser/src/dirt/phishing-detection/services/phishing-data.service.spec.ts b/apps/browser/src/dirt/phishing-detection/services/phishing-data.service.spec.ts
index 0cbb765ce0e..124aa9972e7 100644
--- a/apps/browser/src/dirt/phishing-detection/services/phishing-data.service.spec.ts
+++ b/apps/browser/src/dirt/phishing-detection/services/phishing-data.service.spec.ts
@@ -254,6 +254,74 @@ describe("PhishingDataService", () => {
         (PhishingDataService as any).USE_CUSTOM_MATCHER = originalValue;
       }
     });
+
+    it("should detect HTTPS URL when block list contains HTTP version", async () => {
+      mockIndexedDbService.hasUrl.mockImplementation(async (url: string) => {
+        return url === "http://phish.com/malicious-page";
+      });
+
+      const url = new URL("https://phish.com/malicious-page");
+      const result = await service.isPhishingWebAddress(url);
+
+      expect(result).toBe(true);
+      expect(mockIndexedDbService.hasUrl).toHaveBeenCalledWith("https://phish.com/malicious-page");
+      expect(mockIndexedDbService.hasUrl).toHaveBeenCalledWith("http://phish.com/malicious-page");
+    });
+
+    it("should detect HTTP URL when block list contains HTTPS version", async () => {
+      mockIndexedDbService.hasUrl.mockImplementation(async (url: string) => {
+        return url === "https://phish.com/malicious-page";
+      });
+
+      const url = new URL("http://phish.com/malicious-page");
+      const result = await service.isPhishingWebAddress(url);
+
+      expect(result).toBe(true);
+      expect(mockIndexedDbService.hasUrl).toHaveBeenCalledWith("http://phish.com/malicious-page");
+      expect(mockIndexedDbService.hasUrl).toHaveBeenCalledWith("https://phish.com/malicious-page");
+    });
+
+    it("should detect HTTPS URL with trailing slash when block list contains HTTP without trailing slash", async () => {
+      mockIndexedDbService.hasUrl.mockImplementation(async (url: string) => {
+        return url === "http://phish.com";
+      });
+
+      // Browsers add trailing slash to root URLs: https://phish.com/
+      const url = new URL("https://phish.com");
+      const result = await service.isPhishingWebAddress(url);
+
+      expect(result).toBe(true);
+    });
+
+    it("should not perform alternate-protocol lookup when exact match is found", async () => {
+      mockIndexedDbService.hasUrl.mockImplementation(async (url: string) => {
+        return url === "https://phish.com/exact";
+      });
+
+      const url = new URL("https://phish.com/exact");
+      const result = await service.isPhishingWebAddress(url);
+
+      expect(result).toBe(true);
+      // Should have been called only once (exact match found on first try)
+      expect(mockIndexedDbService.hasUrl).toHaveBeenCalledTimes(1);
+    });
+
+    it("should return false when neither protocol matches", async () => {
+      mockIndexedDbService.hasUrl.mockResolvedValue(false);
+
+      const url = new URL("https://safe-site.com/page");
+      const result = await service.isPhishingWebAddress(url);
+
+      expect(result).toBe(false);
+    });
+
+    it("should skip non-http protocols without alternate lookup", async () => {
+      const url = new URL("ftp://phish.com/file");
+      const result = await service.isPhishingWebAddress(url);
+
+      expect(result).toBe(false);
+      expect(mockIndexedDbService.hasUrl).not.toHaveBeenCalled();
+    });
   });
 
   describe("data updates", () => {
diff --git a/apps/browser/src/dirt/phishing-detection/services/phishing-data.service.ts b/apps/browser/src/dirt/phishing-detection/services/phishing-data.service.ts
index 72415dbbdbe..1014f4cc1fc 100644
--- a/apps/browser/src/dirt/phishing-detection/services/phishing-data.service.ts
+++ b/apps/browser/src/dirt/phishing-detection/services/phishing-data.service.ts
@@ -182,6 +182,23 @@ export class PhishingDataService {
         hasUrl = await this.indexedDbService.hasUrl(urlWithoutTrailingSlash);
       }
 
+      // Check alternate protocol: block list may have http:// but browser navigated to https:// (or vice versa)
+      if (!hasUrl) {
+        const alternateHref = this.swapProtocol(urlHref);
+        if (alternateHref) {
+          hasUrl = await this.indexedDbService.hasUrl(alternateHref);
+
+          if (!hasUrl) {
+            const alternateWithoutTrailingSlash = alternateHref.endsWith("/")
+              ? alternateHref.slice(0, -1)
+              : null;
+            if (alternateWithoutTrailingSlash) {
+              hasUrl = await this.indexedDbService.hasUrl(alternateWithoutTrailingSlash);
+            }
+          }
+        }
+      }
+
       if (hasUrl) {
         this.logService.info("[PhishingDataService] Found phishing URL: " + urlHref);
         return true;
@@ -210,6 +227,20 @@ export class PhishingDataService {
     return false;
   }
 
+  /**
+   * Swaps the protocol of a URL string between http:// and https://.
+   * Returns null if the URL doesn't start with either protocol.
+   */
+  private swapProtocol(url: string): string | null {
+    if (url.startsWith("https://")) {
+      return "http://" + url.slice(8);
+    }
+    if (url.startsWith("http://")) {
+      return "https://" + url.slice(7);
+    }
+    return null;
+  }
+
   // [FIXME] Pull fetches into api service
   private async fetchPhishingChecksum(type: PhishingResourceType = PhishingResourceType.Domains) {
     const checksumUrl = getPhishingResources(type)!.checksumUrl;