diff --git a/CHANGELOG.md b/CHANGELOG.md
index f551d0cd..19385029 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,14 @@
 # Changelog
 
+* Properly provide a third argument to the `table_cell` callback indicating
+  whether the current cell is part of the header or not.
+
+  The previous implementation with two parameters is still supported.
+
+  Fixes #604, Refs #605.
+
+  *Mark Lambley*
+
 * Fix anchor generation on titles with ampersands.
 
   Fixes #696.
diff --git a/README.markdown b/README.markdown
index 7775d57e..b9764ba0 100644
--- a/README.markdown
+++ b/README.markdown
@@ -258,7 +258,7 @@ end
 * paragraph(text)
 * table(header, body)
 * table_row(content)
-* table_cell(content, alignment)
+* table_cell(content, alignment, header)
 
 ### Span-level calls
 
diff --git a/ext/redcarpet/rc_render.c b/ext/redcarpet/rc_render.c
index 26568ac7..e527c1c8 100644
--- a/ext/redcarpet/rc_render.c
+++ b/ext/redcarpet/rc_render.c
@@ -113,9 +113,10 @@ rndr_tablerow(struct buf *ob, const struct buf *text, void *opaque)
 static void
 rndr_tablecell(struct buf *ob, const struct buf *text, int align, void *opaque)
 {
-	VALUE rb_align;
+	VALUE rb_align, rb_header;
+	VALUE rb_callback, rb_callback_arity;
 
-	switch (align) {
+	switch (align & MKD_TABLE_ALIGNMASK) {
 	case MKD_TABLE_ALIGN_L:
 		rb_align = CSTR2SYM("left");
 		break;
@@ -133,7 +134,25 @@ rndr_tablecell(struct buf *ob, const struct buf *text, int align, void *opaque)
 		break;
 	}
 
-	BLOCK_CALLBACK("table_cell", 2, buf2str(text), rb_align);
+	if (align & MKD_TABLE_HEADER) {
+		rb_header = Qtrue;
+	} else {
+		rb_header = Qfalse;
+	}
+
+	struct redcarpet_renderopt *opt = opaque;
+
+	rb_callback = rb_funcall(opt->self, rb_intern("method"), 1, CSTR2SYM("table_cell"));
+
+	rb_callback_arity = rb_funcall(rb_callback, rb_intern("arity"), 0);
+
+	/* For backward compatibility, let's ensure that the erasure with
+	   only two parameters is still supported. */
+	if (FIX2SHORT(rb_callback_arity) == 3) {
+		BLOCK_CALLBACK("table_cell", 3, buf2str(text), rb_align, rb_header);
+	} else {
+		BLOCK_CALLBACK("table_cell", 2, buf2str(text), rb_align);
+	}
 }
 
 static void
diff --git a/test/custom_render_test.rb b/test/custom_render_test.rb
index 87c9f07c..d86ed353 100644
--- a/test/custom_render_test.rb
+++ b/test/custom_render_test.rb
@@ -64,4 +64,43 @@ def test_base_render_without_quote_callback
 
     assert_equal "", parser.render(%(a "quote"))
   end
+
+  def test_table_cell_callback_having_either_two_or_three_args
+    two = Class.new(Redcarpet::Render::HTML) do
+      def table_cell(content, alignment)
+        %(<td>#{content}</td>)
+      end
+    end
+
+    three = Class.new(Redcarpet::Render::HTML) do
+      def table_cell(content, alignment, header)
+        tag = header ? "th" : "td"
+
+        %(<#{tag}>#{content}</#{tag}>)
+      end
+    end
+
+    markdown = <<-Md.chomp.strip_heredoc
+      | A | B |
+      |---|---|
+      | C | D |
+    Md
+
+    first_parser = Redcarpet::Markdown.new(two.new, tables: true)
+    second_parser = Redcarpet::Markdown.new(three.new, tables: true)
+
+    first_output = first_parser.render(markdown)
+    second_output = second_parser.render(markdown)
+
+    assert { first_output.include?("<td>A</td>") }
+    assert { first_output.include?("<td>B</td>") }
+
+    assert { second_output.include?("<th>A</th>") }
+    assert { second_output.include?("<th>B</th>") }
+
+    [first_output, second_output].each do |output|
+      assert { output.include?("<td>C</td>") }
+      assert { output.include?("<td>D</td>") }
+    end
+  end
 end