diff --git a/system/Router/AutoRouterImproved.php b/system/Router/AutoRouterImproved.php
index 0db5ebc1ddc2..63cdd7702635 100644
--- a/system/Router/AutoRouterImproved.php
+++ b/system/Router/AutoRouterImproved.php
@@ -162,7 +162,7 @@ private function searchFirstController(): bool
             $segment = array_shift($segments);
             $controllerPos++;
 
-            $class = $this->translateURIDashes($segment);
+            $class = $this->translateURI($segment);
 
             // as soon as we encounter any segment that is not PSR-4 compliant, stop searching
             if (! $this->isValidSegment($class)) {
@@ -209,7 +209,7 @@ private function searchLastDefaultController(): bool
             }
 
             $namespaces = array_map(
-                fn ($segment) => $this->translateURIDashes($segment),
+                fn ($segment) => $this->translateURI($segment),
                 $segments
             );
 
@@ -307,7 +307,7 @@ public function getRoute(string $uri, string $httpVerb): array
 
         $method = '';
         if ($methodParam !== null) {
-            $method = $httpVerb . $this->translateURIDashes($methodParam);
+            $method = $httpVerb . $this->translateURI($methodParam);
 
             $this->checkUriForMethod($method);
         }
@@ -519,7 +519,17 @@ private function checkUriForMethod(string $method): void
             return;
         }
 
-        if (! in_array($method, get_class_methods($this->controller), true)) {
+        if (
+            // For example, if `getSomeMethod()` exists in the controller, only
+            // the URI `controller/some-method` should be accessible. But if a
+            // visitor navigates to the URI `controller/somemethod`, `getSomemethod()`
+            // will be checked, and `method_exists()` will return true because
+            // method names in PHP are case-insensitive.
+            method_exists($this->controller, $method)
+            // But we do not permit `controller/somemethod`, so check the exact
+            // method name.
+            && ! in_array($method, get_class_methods($this->controller), true)
+        ) {
             throw new PageNotFoundException(
                 '"' . $this->controller . '::' . $method . '()" is not found.'
             );
@@ -536,7 +546,10 @@ private function isValidSegment(string $segment): bool
         return (bool) preg_match('/^[a-zA-Z_\x80-\xff][a-zA-Z0-9_\x80-\xff]*$/', $segment);
     }
 
-    private function translateURIDashes(string $segment): string
+    /**
+     * Translates URI segment to CamelCase or replaces `-` with `_`.
+     */
+    private function translateURI(string $segment): string
     {
         if ($this->translateUriToCamelCase) {
             if (strtolower($segment) !== $segment) {
diff --git a/tests/system/Router/AutoRouterImprovedTest.php b/tests/system/Router/AutoRouterImprovedTest.php
index c60c978e4a3c..5975280bcdfd 100644
--- a/tests/system/Router/AutoRouterImprovedTest.php
+++ b/tests/system/Router/AutoRouterImprovedTest.php
@@ -277,6 +277,28 @@ public function testAutoRouteFallbackToDefaultMethod(): void
         ], $router->getPos());
     }
 
+    public function testAutoRouteFallbackToDefaultMethodWithTranslateUriToCamelCase(): void
+    {
+        $config                          = config(Routing::class);
+        $config->translateUriToCamelCase = true;
+        Factories::injectMock('config', Routing::class, $config);
+
+        $router = $this->createNewAutoRouter();
+
+        [$directory, $controller, $method, $params]
+            = $router->getRoute('index/15', Method::GET);
+
+        $this->assertNull($directory);
+        $this->assertSame('\\' . Index::class, $controller);
+        $this->assertSame('getIndex', $method);
+        $this->assertSame(['15'], $params);
+        $this->assertSame([
+            'controller' => 0,
+            'method'     => null,
+            'params'     => 1,
+        ], $router->getPos());
+    }
+
     public function testAutoRouteFallbackToDefaultControllerOneParam(): void
     {
         $router = $this->createNewAutoRouter();