diff --git a/collection.go b/collection.go
index f6754ff..0fa944b 100644
--- a/collection.go
+++ b/collection.go
@@ -10,23 +10,23 @@ import (
 type Collection struct {
 	Site   *Site
 	Name   string
-	Data   map[interface{}]interface{}
+	Data   VariableMap
 	Output bool
 	Pages  []*Page
 }
 
-func makeCollection(s *Site, name string, d map[interface{}]interface{}) *Collection {
+func makeCollection(s *Site, name string, d VariableMap) *Collection {
 	return &Collection{
 		Site:   s,
 		Name:   name,
 		Data:   d,
-		Output: getBool(d, "output", false),
+		Output: d.Bool("output", false),
 	}
 }
 
 // PageArrayVariableValue returns an array of a page data, for use as the template variable
 // value of the collection.
-func (c *Collection) PageArrayVariableValue() (d []interface{}) {
+func (c *Collection) PageArrayVariableValue() (d []VariableMap) {
 	for _, p := range c.Pages {
 		d = append(d, p.PageVariables())
 	}
@@ -34,28 +34,27 @@ func (c *Collection) PageArrayVariableValue() (d []interface{}) {
 }
 
 // Posts returns true if the collection is the special "posts" collection.
-func (c *Collection) Posts() bool {
+func (c *Collection) IsPosts() bool {
 	return c.Name == "posts"
 }
 
-// SourceDir returns the source directory for pages in the collection.
-func (c *Collection) SourceDir() string {
+// Source returns the source directory for pages in the collection.
+func (c *Collection) Source() string {
 	return filepath.Join(c.Site.Source, "_"+c.Name)
 }
 
 // ReadPages scans the file system for collection pages, and adds them to c.Pages.
 func (c *Collection) ReadPages() error {
 	basePath := c.Site.Source
-	d := map[interface{}]interface{}{
+	defaults := mergeVariableMaps(c.Data, VariableMap{
 		"collection": c.Name,
-	}
-	d = mergeMaps(c.Data, d)
+	})
 
 	walkFn := func(path string, info os.FileInfo, err error) error {
 		if err != nil {
-			// if the issue is simply that the directory doesn't exist, ignore the error
+			// if the issue is simply that the directory doesn't exist, warn instead of error
 			if os.IsNotExist(err) {
-				if !c.Posts() {
+				if !c.IsPosts() {
 					fmt.Println("Missing directory for collection", c.Name)
 				}
 				return nil
@@ -69,7 +68,7 @@ func (c *Collection) ReadPages() error {
 		case info.IsDir():
 			return nil
 		}
-		p, err := ReadPage(rel, d)
+		p, err := ReadPage(rel, defaults)
 		switch {
 		case err != nil:
 			return err
@@ -81,5 +80,5 @@ func (c *Collection) ReadPages() error {
 		}
 		return nil
 	}
-	return filepath.Walk(c.SourceDir(), walkFn)
+	return filepath.Walk(c.Source(), walkFn)
 }
diff --git a/helpers.go b/helpers.go
index ddc8e12..1402c40 100644
--- a/helpers.go
+++ b/helpers.go
@@ -28,7 +28,7 @@ func copyFile(dst, src string, perm os.FileMode) error {
 	return outf.Close()
 }
 
-func getBool(m map[interface{}]interface{}, k string, defaultValue bool) bool {
+func (m VariableMap) Bool(k string, defaultValue bool) bool {
 	if val, found := m[k]; found {
 		if v, ok := val.(bool); ok {
 			return v
@@ -37,7 +37,7 @@ func getBool(m map[interface{}]interface{}, k string, defaultValue bool) bool {
 	return defaultValue
 }
 
-func getString(m map[interface{}]interface{}, k string, defaultValue string) string {
+func (m VariableMap) String(k string, defaultValue string) string {
 	if val, found := m[k]; found {
 		if v, ok := val.(string); ok {
 			return v
@@ -58,8 +58,8 @@ func LeftPad(s string, n int) string {
 	return string(ws) + s
 }
 
-func mergeMaps(a map[interface{}]interface{}, b map[interface{}]interface{}) map[interface{}]interface{} {
-	result := map[interface{}]interface{}{}
+func mergeVariableMaps(a VariableMap, b VariableMap) VariableMap {
+	result := VariableMap{}
 	for k, v := range a {
 		result[k] = v
 	}
@@ -69,10 +69,10 @@ func mergeMaps(a map[interface{}]interface{}, b map[interface{}]interface{}) map
 	return result
 }
 
-// stringMap returns a string-indexed map with the same values as its argument.
+// makeVariableMap returns a string-indexed map with the same values as its argument.
 // Non-strings keys are converted to strings.
-func stringMap(m map[interface{}]interface{}) map[string]interface{} {
-	result := map[string]interface{}{}
+func makeVariableMap(m map[interface{}]interface{}) VariableMap {
+	result := VariableMap{}
 	for k, v := range m {
 		stringer, ok := k.(fmt.Stringer)
 		if ok {
diff --git a/helpers_test.go b/helpers_test.go
index 6dc1b13..882fd94 100644
--- a/helpers_test.go
+++ b/helpers_test.go
@@ -13,37 +13,37 @@ func TestLeftPad(t *testing.T) {
 }
 
 func TestGetXXX(t *testing.T) {
-	d := map[interface{}]interface{}{
+	d := VariableMap{
 		"t": true,
 		"f": false,
 		"s": "ss",
 	}
-	assert.Equal(t, true, getBool(d, "t", true))
-	assert.Equal(t, true, getBool(d, "t", false))
-	assert.Equal(t, false, getBool(d, "f", true))
-	assert.Equal(t, false, getBool(d, "f", true))
-	assert.Equal(t, true, getBool(d, "-", true))
-	assert.Equal(t, false, getBool(d, "-", false))
-	assert.Equal(t, true, getBool(d, "s", true))
-	assert.Equal(t, false, getBool(d, "s", false))
+	assert.Equal(t, true, d.Bool("t", true))
+	assert.Equal(t, true, d.Bool("t", false))
+	assert.Equal(t, false, d.Bool("f", true))
+	assert.Equal(t, false, d.Bool("f", true))
+	assert.Equal(t, true, d.Bool("-", true))
+	assert.Equal(t, false, d.Bool("-", false))
+	assert.Equal(t, true, d.Bool("s", true))
+	assert.Equal(t, false, d.Bool("s", false))
 
-	assert.Equal(t, "ss", getString(d, "s", "-"))
-	assert.Equal(t, "--", getString(d, "-", "--"))
-	assert.Equal(t, "--", getString(d, "t", "--"))
+	assert.Equal(t, "ss", d.String("s", "-"))
+	assert.Equal(t, "--", d.String("-", "--"))
+	assert.Equal(t, "--", d.String("t", "--"))
 }
 
-func TestMergeMaps(t *testing.T) {
-	m1 := map[interface{}]interface{}{"a": 1, "b": 2}
-	m2 := map[interface{}]interface{}{"b": 3, "c": 4}
-	expected := map[interface{}]interface{}{"a": 1, "b": 3, "c": 4}
-	actual := mergeMaps(m1, m2)
+func TestMakeVariableMap(t *testing.T) {
+	input := map[interface{}]interface{}{"a": 1, 10: 2, false: 3}
+	expected := VariableMap{"a": 1, "10": 2, "false": 3}
+	actual := makeVariableMap(input)
 	assert.Equal(t, expected, actual)
 }
 
-func TestStringMap(t *testing.T) {
-	input := map[interface{}]interface{}{"a": 1, 10: 2, false: 3}
-	expected := map[string]interface{}{"a": 1, "10": 2, "false": 3}
-	actual := stringMap(input)
+func TestMergeVariableMaps(t *testing.T) {
+	m1 := VariableMap{"a": 1, "b": 2}
+	m2 := VariableMap{"b": 3, "c": 4}
+	expected := VariableMap{"a": 1, "b": 3, "c": 4}
+	actual := mergeVariableMaps(m1, m2)
 	assert.Equal(t, expected, actual)
 }
 
diff --git a/main.go b/main.go
index 5d7cbf4..1bbe2d2 100644
--- a/main.go
+++ b/main.go
@@ -160,9 +160,9 @@ func dataCommand(c *cli.Context) error {
 	// Neuter it. This destroys it as Liquid data, but that's okay in this context.
 	data := site.Variables
 	for _, c := range site.Collections {
-		data[c.Name] = fmt.Sprintf("<elided page data for %d items>", len(data[c.Name].([]interface{})))
+		data[c.Name] = fmt.Sprintf("<elided page data for %d items>", len(data[c.Name].([]VariableMap)))
 	}
-	b, _ := yaml.Marshal(stringMap(page.Data()))
+	b, _ := yaml.Marshal(page.Data())
 	fmt.Println(string(b))
 	return nil
 }
diff --git a/page.go b/page.go
index 0e65935..733154d 100644
--- a/page.go
+++ b/page.go
@@ -22,6 +22,8 @@ var (
 	nonAlphanumericSequenceMatcher = regexp.MustCompile(`[^[:alnum:]]+`)
 )
 
+type VariableMap map[string]interface{}
+
 var permalinkStyles = map[string]string{
 	"date":    "/:categories/:year/:month/:day/:title.html",
 	"pretty":  "/:categories/:year/:month/:day/:title/",
@@ -35,7 +37,7 @@ type Page struct {
 	Permalink   string
 	Static      bool
 	Published   bool
-	FrontMatter map[interface{}]interface{}
+	FrontMatter VariableMap
 	Content     []byte
 }
 
@@ -45,11 +47,11 @@ func (p *Page) String() string {
 }
 
 // PageVariables returns metadata for use in the representation of the page as a collection item
-func (p *Page) PageVariables() map[interface{}]interface{} {
+func (p *Page) PageVariables() VariableMap {
 	if p.Static {
-		return mergeMaps(p.FrontMatter, p.staticFileData())
+		return mergeVariableMaps(p.FrontMatter, p.staticFileData())
 	}
-	data := map[interface{}]interface{}{
+	data := VariableMap{
 		"url":  p.Permalink,
 		"path": p.Source(),
 		// TODO content title excerpt date id categories tags next previous
@@ -68,14 +70,14 @@ func (p *Page) PageVariables() map[interface{}]interface{} {
 	return data
 }
 
-func (p *Page) staticFileData() map[interface{}]interface{} {
+func (p *Page) staticFileData() VariableMap {
 	var (
 		path = "/" + p.Path
 		base = filepath.Base(path)
 		ext  = filepath.Ext(path)
 	)
 
-	return map[interface{}]interface{}{
+	return VariableMap{
 		"path":          path,
 		"modified_time": 0, // TODO
 		"name":          base,
@@ -85,17 +87,17 @@ func (p *Page) staticFileData() map[interface{}]interface{} {
 }
 
 // Data returns the variable context for Liquid evaluation
-func (p *Page) Data() map[interface{}]interface{} {
-	return map[interface{}]interface{}{
+func (p *Page) Data() VariableMap {
+	return VariableMap{
 		"page": p.PageVariables(),
 		"site": site.Variables,
 	}
 }
 
 // ReadPage reads a Page from a file, using defaults as the default front matter.
-func ReadPage(path string, defaults map[interface{}]interface{}) (p *Page, err error) {
+func ReadPage(path string, defaults VariableMap) (p *Page, err error) {
 	var (
-		frontMatter map[interface{}]interface{}
+		frontMatter VariableMap
 		static      = true
 		body        []byte
 	)
@@ -112,14 +114,14 @@ func ReadPage(path string, defaults map[interface{}]interface{}) (p *Page, err e
 		body = append(
 			regexp.MustCompile(`[^\n\r]+`).ReplaceAllLiteral(source[:match[1]], []byte{}),
 			source[match[1]:]...)
-		frontMatter = map[interface{}]interface{}{}
+		frontMatter = VariableMap{}
 		err = yaml.Unmarshal(source[match[2]:match[3]], &frontMatter)
 		if err != nil {
 			err := &os.PathError{Op: "read frontmatter", Path: path, Err: err}
 			return nil, err
 		}
 
-		frontMatter = mergeMaps(defaults, frontMatter)
+		frontMatter = mergeVariableMaps(defaults, frontMatter)
 	} else {
 		frontMatter = defaults
 		body = []byte{}
@@ -145,7 +147,7 @@ func ReadPage(path string, defaults map[interface{}]interface{}) (p *Page, err e
 		Path:        path,
 		Permalink:   permalink,
 		Static:      static,
-		Published:   getBool(data, "published", true),
+		Published:   data.Bool("published", true),
 		FrontMatter: data,
 		Content:     body,
 	}
@@ -182,7 +184,7 @@ func (p *Page) Render(w io.Writer) error {
 		return err
 	}
 	writer := new(bytes.Buffer)
-	template.Render(writer, stringMap(p.Data()))
+	template.Render(writer, p.Data())
 	body := writer.Bytes()
 
 	if isMarkdown(p.Path) {
@@ -198,7 +200,7 @@ func isMarkdown(path string) bool {
 	return site.MarkdownExtensions()[strings.TrimLeft(ext, ".")]
 }
 
-func permalinkTemplateVariables(path string, data map[interface{}]interface{}) map[string]string {
+func permalinkTemplateVariables(path string, data VariableMap) map[string]string {
 	var (
 		collectionName string
 		localPath      = path
@@ -206,7 +208,7 @@ func permalinkTemplateVariables(path string, data map[interface{}]interface{}) m
 		root           = path[:len(path)-len(ext)]
 		outputExt      = ext
 		name           = filepath.Base(root)
-		title          = getString(data, "title", name)
+		title          = data.String("title", name)
 	)
 
 	if isMarkdown(path) {
@@ -235,7 +237,7 @@ func permalinkTemplateVariables(path string, data map[interface{}]interface{}) m
 	}
 }
 
-func expandPermalinkPattern(pattern string, path string, data map[interface{}]interface{}) (s string, err error) {
+func expandPermalinkPattern(pattern string, path string, data VariableMap) (s string, err error) {
 	if p, found := permalinkStyles[pattern]; found {
 		pattern = p
 	}
diff --git a/permalinks_test.go b/permalinks_test.go
index d182eb7..5dae4c4 100644
--- a/permalinks_test.go
+++ b/permalinks_test.go
@@ -8,7 +8,7 @@ import (
 
 func TestExpandPermalinkPattern(t *testing.T) {
 	var (
-		d      = map[interface{}]interface{}{}
+		d      = VariableMap{}
 		path   = "/a/b/c.d"
 		mdPath = "/a/b/c.md"
 	)
diff --git a/site.go b/site.go
index 1aa729e..b7edbbd 100644
--- a/site.go
+++ b/site.go
@@ -16,7 +16,7 @@ type Site struct {
 	Dest       string
 
 	Collections []*Collection
-	Variables   map[interface{}]interface{}
+	Variables   VariableMap
 	Paths       map[string]*Page // URL path -> *Page
 
 	config SiteConfig
@@ -31,7 +31,7 @@ type SiteConfig struct {
 	// Where things are:
 	Source      string
 	Destination string
-	Collections map[string]interface{}
+	Collections map[string]VariableMap
 
 	// Handling Reading
 	Include     []string
@@ -102,14 +102,14 @@ func (s *Site) ReadConfiguration(source, dest string) error {
 }
 
 func (s *Site) readConfigBytes(bytes []byte) error {
-	configVariables := map[interface{}]interface{}{}
+	configVariables := VariableMap{}
 	if err := yaml.Unmarshal(bytes, &s.config); err != nil {
 		return err
 	}
 	if err := yaml.Unmarshal(bytes, &configVariables); err != nil {
 		return err
 	}
-	s.Variables = mergeMaps(s.Variables, configVariables)
+	s.Variables = mergeVariableMaps(s.Variables, configVariables)
 	return nil
 }
 
@@ -158,7 +158,7 @@ func (s *Site) Exclude(path string) bool {
 // ReadFiles scans the source directory and creates pages and collections.
 func (s *Site) ReadFiles() error {
 	s.Paths = make(map[string]*Page)
-	defaults := map[interface{}]interface{}{}
+	defaults := VariableMap{}
 
 	walkFn := func(path string, info os.FileInfo, err error) error {
 		if err != nil {
@@ -199,11 +199,7 @@ func (s *Site) ReadFiles() error {
 // pages to the site map, and creates a template site variable for each collection.
 func (s *Site) readCollections() error {
 	for name, d := range s.config.Collections {
-		data, ok := d.(map[interface{}]interface{})
-		if !ok {
-			panic("expected collection value to be a map")
-		}
-		c := makeCollection(s, name, data)
+		c := makeCollection(s, name, d)
 		s.Collections = append(s.Collections, c)
 		if c.Output { // TODO always read the pages; just don't build them / include them in routes
 			if err := c.ReadPages(); err != nil {