diff --git a/engine_test.go b/engine_test.go
index 334d674..4a56258 100644
--- a/engine_test.go
+++ b/engine_test.go
@@ -66,6 +66,17 @@ func TestEngine_ParseAndRenderString_struct(t *testing.T) {
 	require.Equal(t, "hello", str)
 }
 
+func TestEngine_ParseAndRender_errors(t *testing.T) {
+	_, err := NewEngine().ParseAndRenderString("{{ syntax error }}", emptyBindings)
+	require.Error(t, err)
+	_, err = NewEngine().ParseAndRenderString("{% if %}", emptyBindings)
+	require.Error(t, err)
+	_, err = NewEngine().ParseAndRenderString("{% undefined_tag %}", emptyBindings)
+	require.Error(t, err)
+	_, err = NewEngine().ParseAndRenderString("{% a | undefined_filter %}", emptyBindings)
+	require.Error(t, err)
+}
+
 func BenchmarkEngine_Parse(b *testing.B) {
 	engine := NewEngine()
 	buf := new(bytes.Buffer)
diff --git a/liquid.go b/liquid.go
index 9f59d3a..c8843eb 100644
--- a/liquid.go
+++ b/liquid.go
@@ -24,6 +24,8 @@ type Bindings map[string]interface{}
 type Renderer func(render.Context) (string, error)
 
 // SourceError records an error with a source location and optional cause.
+//
+// SourceError does not depend on, but is compatible with, the causer interface of https://github.com/pkg/errors.
 type SourceError interface {
 	error
 	Cause() error
diff --git a/liquid_test.go b/liquid_test.go
deleted file mode 100644
index 23143ba..0000000
--- a/liquid_test.go
+++ /dev/null
@@ -1,18 +0,0 @@
-package liquid
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/require"
-)
-
-func TestIsTemplateError(t *testing.T) {
-	_, err := NewEngine().ParseAndRenderString("{{ syntax error }}", emptyBindings)
-	require.Error(t, err)
-	_, err = NewEngine().ParseAndRenderString("{% if %}", emptyBindings)
-	require.Error(t, err)
-	_, err = NewEngine().ParseAndRenderString("{% undefined_tag %}", emptyBindings)
-	require.Error(t, err)
-	_, err = NewEngine().ParseAndRenderString("{% a | undefined_filter %}", emptyBindings)
-	require.Error(t, err)
-}
diff --git a/tags/include_tag_test.go b/tags/include_tag_test.go
index 1698dba..cd4be29 100644
--- a/tags/include_tag_test.go
+++ b/tags/include_tag_test.go
@@ -11,23 +11,42 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-var includeTestBindings = map[string]interface{}{}
+var includeTestBindings = map[string]interface{}{
+	"test": true,
+	"var":  "value",
+}
 
 func TestIncludeTag(t *testing.T) {
 	config := render.NewConfig()
 	loc := parser.SourceLoc{Pathname: "testdata/include_source.html", LineNo: 1}
 	AddStandardTags(config)
 
-	ast, err := config.Compile(`{% include "include_target.html" %}`, loc)
+	// basic functionality
+	root, err := config.Compile(`{% include "include_target.html" %}`, loc)
 	require.NoError(t, err)
 	buf := new(bytes.Buffer)
-	err = render.Render(ast, buf, includeTestBindings, config)
+	err = render.Render(root, buf, includeTestBindings, config)
 	require.NoError(t, err)
 	require.Equal(t, "include target", strings.TrimSpace(buf.String()))
 
-	ast, err = config.Compile(`{% include 10 %}`, loc)
+	// tag and variable
+	root, err = config.Compile(`{% include "include_target_2.html" %}`, loc)
 	require.NoError(t, err)
-	err = render.Render(ast, ioutil.Discard, includeTestBindings, config)
+	buf = new(bytes.Buffer)
+	err = render.Render(root, buf, includeTestBindings, config)
+	require.NoError(t, err)
+	require.Equal(t, "value", strings.TrimSpace(buf.String()))
+
+	// errors
+	root, err = config.Compile(`{% include 10 %}`, loc)
+	require.NoError(t, err)
+	err = render.Render(root, ioutil.Discard, includeTestBindings, config)
 	require.Error(t, err)
 	require.Contains(t, err.Error(), "requires a string")
+
+	root, err = config.Compile(`{% include "missing_file.html" %}`, loc)
+	require.NoError(t, err)
+	err = render.Render(root, ioutil.Discard, includeTestBindings, config)
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "no such file")
 }
diff --git a/tags/testdata/include_target_2.html b/tags/testdata/include_target_2.html
new file mode 100644
index 0000000..519b97a
--- /dev/null
+++ b/tags/testdata/include_target_2.html
@@ -0,0 +1 @@
+{% if test %}{{ var }}{% endif %}
\ No newline at end of file