diff --git a/lib/liquid/context.rb b/lib/liquid/context.rb
index 1ef272d46..433b6d003 100644
--- a/lib/liquid/context.rb
+++ b/lib/liquid/context.rb
@@ -184,7 +184,7 @@ def [](expression)
     end
 
     def key?(key)
-      self[key] != nil
+      find_variable(key, raise_on_not_found: false) != nil
     end
 
     def evaluate(object)
diff --git a/test/integration/context_test.rb b/test/integration/context_test.rb
index f59147e29..d230734f6 100644
--- a/test/integration/context_test.rb
+++ b/test/integration/context_test.rb
@@ -639,6 +639,21 @@ def test_has_key_will_not_add_an_error_for_missing_keys
     end
   end
 
+  def test_key_lookup_will_raise_for_missing_keys_when_strict_variables_is_enabled
+    context = Context.new
+    context.strict_variables = true
+    assert_raises(Liquid::UndefinedVariable) do
+      context['unknown']
+    end
+  end
+
+  def test_has_key_will_not_raise_for_missing_keys_when_strict_variables_is_enabled
+    context = Context.new
+    context.strict_variables = true
+    refute(context.key?('unknown'))
+    assert_empty(context.errors)
+  end
+
   def test_context_always_uses_static_registers
     registers = {
       my_register: :my_value,