diff --git a/lib/spark.ex b/lib/spark.ex
index 21ee0ea..5a43a4f 100644
--- a/lib/spark.ex
+++ b/lib/spark.ex
@@ -46,7 +46,7 @@ defmodule Spark do
 
       # never seen a module with three behaviours in real life, let alone four.
       {:behaviour, behaviours} when is_list(behaviours) ->
-        module in behaviours
+        behaviour in behaviours
 
       _ ->
         false
diff --git a/test/spark_test.exs b/test/spark_test.exs
index f0d921e..2b8fa5e 100644
--- a/test/spark_test.exs
+++ b/test/spark_test.exs
@@ -6,4 +6,19 @@ defmodule SparkTest do
   use ExUnit.Case
   doctest Spark
   doctest Spark.Options
+
+  describe inspect(&Spark.implements_behaviour?/2) do
+    test "returns true if the module implements the specified behavior" do
+      defmodule TestModule do
+        @callback foo :: any()
+
+        @behaviour TestModule
+
+        def foo, do: :ok
+      end
+
+      refute Spark.implements_behaviour?(TestModule, AnyOtherModule)
+      assert Spark.implements_behaviour?(TestModule, TestModule)
+    end
+  end
 end