diff --git a/src/ParserContext.php b/src/ParserContext.php
index a3770c2..c872c80 100644
--- a/src/ParserContext.php
+++ b/src/ParserContext.php
@@ -34,6 +34,12 @@ public function disableExtensions(): this {
     return $this;
   }
 
+  public function disableNamedExtension(string $name): this {
+    $this->blockContext->disableNamedExtension($name);
+    $this->inlineContext->disableNamedExtension($name);
+    return $this;
+  }
+
   public function enableNamedExtension(string $name): this {
     $this->blockContext->enableNamedExtension($name);
     $this->inlineContext->enableNamedExtension($name);
diff --git a/src/inlines/Context.php b/src/inlines/Context.php
index fd0c955..2c1cd4f 100644
--- a/src/inlines/Context.php
+++ b/src/inlines/Context.php
@@ -74,12 +74,23 @@ public function disableExtensions(): this {
     return $this;
   }
 
+  public function disableNamedExtension(string $name): this {
+    $this->disabledInlineTypes = Keyset\union(
+      $this->disabledInlineTypes,
+      Keyset\filter(
+        self::ALL_INLINE_TYPES,
+        $class ==> Str\ends_with(Str\lowercase($class), "\\".$name.'extension'),
+      ),
+    );
+    return $this;
+  }
+
   public function enableNamedExtension(string $name): this {
     $this->disabledInlineTypes = Keyset\filter(
       $this->disabledInlineTypes,
       $class ==> !Str\ends_with(
         Str\lowercase($class),
-        "\\".$name.'extension',
+        "\\".Str\lowercase($name).'extension',
       ),
     );
     return $this;
diff --git a/src/render/RenderContext.php b/src/render/RenderContext.php
index e367ec1..b284985 100644
--- a/src/render/RenderContext.php
+++ b/src/render/RenderContext.php
@@ -34,6 +34,14 @@ public function disableExtensions(): this {
     return $this;
   }
 
+  public function disableNamedExtension(string $extension): this {
+    $this->enabledExtensions = Vec\filter(
+      $this->enabledExtensions,
+      $obj ==> !Str\ends_with_ci(\get_class($obj), "\\".$extension.'Extension'),
+    );
+    return $this;
+  }
+
   public function enableNamedExtension(string $extension): this {
     $this->enabledExtensions = $this->extensions
       |> Vec\filter(
diff --git a/src/unparsed-blocks/Context.php b/src/unparsed-blocks/Context.php
index d675c07..5211b51 100644
--- a/src/unparsed-blocks/Context.php
+++ b/src/unparsed-blocks/Context.php
@@ -49,6 +49,20 @@ public function disableExtensions(): this {
     return $this;
   }
 
+  public function disableNamedExtension(string $name): this {
+    $this->disabledBlockTypes = Keyset\union(
+      $this->disabledBlockTypes,
+      Keyset\filter(
+        self::ALL_BLOCK_TYPES,
+        $class ==> Str\ends_with(
+          Str\lowercase($class),
+          "\\".Str\lowercase($name).'extension',
+        ),
+      ),
+    );
+    return $this;
+  }
+
   public function enableNamedExtension(string $name): this {
     $this->disabledBlockTypes = Keyset\filter(
       $this->disabledBlockTypes,
diff --git a/tests/EdgeCaseTest.php b/tests/EdgeCaseTest.php
index 5a86d4c..aa31d98 100644
--- a/tests/EdgeCaseTest.php
+++ b/tests/EdgeCaseTest.php
@@ -49,4 +49,16 @@ public function testManualExample(
       null,
     );
   }
+
+  public function testTagFilter(): void {
+    $ast = parse((new ParserContext())->enableHTML_UNSAFE(), '<iframe />');
+    $html = (new HTMLRenderer(new RenderContext()))->render($ast);
+    expect($html)->toBeSame("&lt;iframe />\n");
+    $html = (
+      new HTMLRenderer(
+        (new RenderContext())->disableNamedExtension('TagFilter'),
+      )
+    )->render($ast);
+    expect($html)->toBeSame("<iframe />\n");
+  }
 }