diff --git a/app/src/main/java/org/mozilla/fenix/customtabs/FennecWebAppIntentProcessor.kt b/app/src/main/java/org/mozilla/fenix/customtabs/FennecWebAppIntentProcessor.kt
index ee5c9f94f..1eee927a2 100644
--- a/app/src/main/java/org/mozilla/fenix/customtabs/FennecWebAppIntentProcessor.kt
+++ b/app/src/main/java/org/mozilla/fenix/customtabs/FennecWebAppIntentProcessor.kt
@@ -106,7 +106,7 @@ class FennecWebAppIntentProcessor(
         if (path.isNullOrEmpty()) return null
 
         val file = File(path)
-        if (!file.isUnderFennecManifestDirectory()) return null
+        if (!isUnderFennecManifestDirectory(file)) return null
 
         return try {
             // Gecko in Fennec added some add some additional data, such as cached_icon, in
@@ -127,12 +127,13 @@ class FennecWebAppIntentProcessor(
     /**
      * Fennec manifests should be located in <filesDir>/mozilla/<profile>/manifests/
      */
-    private fun File.isUnderFennecManifestDirectory(): Boolean {
-        val manifestsDir = canonicalFile.parentFile
+    @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
+    internal fun isUnderFennecManifestDirectory(file: File): Boolean {
+        val manifestsDir = file.canonicalFile.parentFile
         // Check that manifest is in a folder named "manifests"
-        return manifestsDir == null || manifestsDir.name != "manifests" ||
+        return manifestsDir != null && manifestsDir.name == "manifests" &&
             // Check that the folder two levels up is named "mozilla"
-            manifestsDir.parentFile?.parentFile != getMozillaDirectory()
+            manifestsDir.parentFile?.parentFile?.canonicalPath == getMozillaDirectory().canonicalPath
     }
 
     private fun createFallbackCustomTabConfig(): CustomTabConfig {
diff --git a/app/src/test/java/org/mozilla/fenix/customtabs/FennecWebAppIntentProcessorTest.kt b/app/src/test/java/org/mozilla/fenix/customtabs/FennecWebAppIntentProcessorTest.kt
new file mode 100644
index 000000000..6e9f7c715
--- /dev/null
+++ b/app/src/test/java/org/mozilla/fenix/customtabs/FennecWebAppIntentProcessorTest.kt
@@ -0,0 +1,73 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.customtabs
+
+import io.mockk.mockk
+import mozilla.components.browser.session.SessionManager
+import mozilla.components.feature.pwa.ManifestStorage
+import mozilla.components.feature.session.SessionUseCases
+import mozilla.components.support.test.robolectric.testContext
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mozilla.fenix.helpers.FenixRobolectricTestRunner
+import java.io.File
+
+@RunWith(FenixRobolectricTestRunner::class)
+class FennecWebAppIntentProcessorTest {
+    @Test
+    fun `fennec manifest path - tmp`() {
+        val processor = createFennecWebAppIntentProcessor()
+
+        val file = File("/data/local/tmp/dummy_manifest.json")
+        assertFalse(processor.isUnderFennecManifestDirectory(file))
+    }
+
+    @Test
+    fun `fennec manifest path - correct path`() {
+        val processor = createFennecWebAppIntentProcessor()
+
+        val file = File(testContext.filesDir.absolutePath + "/mozilla/rkgl5eyc.default/manifests/c311ad28-f331-482f-ba8f-a0fbf2c56a0d.json")
+        assertTrue(processor.isUnderFennecManifestDirectory(file))
+    }
+
+    @Test
+    fun `fennec manifest path - correct path, but other app`() {
+        val processor = createFennecWebAppIntentProcessor()
+
+        val file = File("/data/data/org.other.app/files/mozilla/rkgl5eyc.default/manifests/c311ad28-f331-482f-ba8f-a0fbf2c56a0d.json")
+        assertFalse(processor.isUnderFennecManifestDirectory(file))
+    }
+
+    @Test
+    fun `fennec manifest path - root file`() {
+        val processor = createFennecWebAppIntentProcessor()
+
+        val file = File("/c311ad28-f331-482f-ba8f-a0fbf2c56a0d.json")
+        assertFalse(processor.isUnderFennecManifestDirectory(file))
+    }
+
+    @Test
+    fun `fennec manifest path - tmp path rebuild`() {
+        val processor = createFennecWebAppIntentProcessor()
+
+        val file = File("/data/local/tmp/files/mozilla/rkgl5eyc.default/manifests/c311ad28-f331-482f-ba8f-a0fbf2c56a0d.json")
+        assertFalse(processor.isUnderFennecManifestDirectory(file))
+    }
+}
+
+private fun createFennecWebAppIntentProcessor(): FennecWebAppIntentProcessor {
+    val sessionManager = SessionManager(engine = mockk(relaxed = true))
+    val useCase: SessionUseCases.DefaultLoadUrlUseCase = mockk(relaxed = true)
+    val storage: ManifestStorage = mockk(relaxed = true)
+
+    return FennecWebAppIntentProcessor(
+        testContext,
+        sessionManager,
+        useCase,
+        storage
+    )
+}