diff --git a/README.md b/README.md
index 8af9711..e1ef4e8 100644
--- a/README.md
+++ b/README.md
@@ -136,6 +136,10 @@ err := gen.Generate()
 ## Config
 
 ```yaml
+# You can specify default mappings that will apply to all packages.
+type_mappings:
+  time.Time: "string /* RFC3339 */"
+  
 # You can specify more than one package
 packages:
   # The package path just like you would import it in Go
@@ -149,7 +153,8 @@ packages:
     indent: "    "
 
     # Specify your own custom type translations, useful for custom types, `time.Time` and `null.String`.
-    # Be default unrecognized types will be `any`.
+    # By default unrecognized types will be `any`.
+    # A mapping specified here will override one specified globally.
     type_mappings:
       time.Time: "string"
       my.Type: "SomeType"
diff --git a/examples/globalconfig/globalconfig.go b/examples/globalconfig/globalconfig.go
new file mode 100644
index 0000000..ac79b02
--- /dev/null
+++ b/examples/globalconfig/globalconfig.go
@@ -0,0 +1,7 @@
+package globalconfig
+
+import "time"
+
+type Config struct {
+	Duration time.Duration
+}
diff --git a/tygo.yaml b/tygo.yaml
index 32c5f5b..396bb09 100644
--- a/tygo.yaml
+++ b/tygo.yaml
@@ -1,5 +1,7 @@
 # This is a config file that typescriptifies the packages under the example folder.
 # and some other packages.
+type_mappings:
+  time.Duration: "number /* int, ns */"
 
 packages:
   - path: "github.com/gzuidhof/tygo/examples/bookstore"
@@ -56,4 +58,6 @@ packages:
       - "excluded.go"
   - path: "github.com/gzuidhof/tygo/examples/rune"
 
+  - path: "github.com/gzuidhof/tygo/examples/globalconfig"
+  
 
diff --git a/tygo/config.go b/tygo/config.go
index 105b86a..bcb28aa 100644
--- a/tygo/config.go
+++ b/tygo/config.go
@@ -64,7 +64,8 @@ type PackageConfig struct {
 }
 
 type Config struct {
-	Packages []*PackageConfig `yaml:"packages"`
+	TypeMappings map[string]string `yaml:"type_mappings"`
+	Packages     []*PackageConfig  `yaml:"packages"`
 }
 
 func (c Config) PackageNames() []string {
@@ -79,6 +80,7 @@ func (c Config) PackageNames() []string {
 func (c Config) PackageConfig(packagePath string) *PackageConfig {
 	for _, pc := range c.Packages {
 		if pc.Path == packagePath {
+			pc.TypeMappings = c.mergeMappings(pc.TypeMappings)
 			pcNormalized, err := pc.Normalize()
 			if err != nil {
 				log.Fatalf("Error in config for package %s: %s", packagePath, err)
@@ -188,3 +190,14 @@ func (pc PackageConfig) Normalize() (PackageConfig, error) {
 
 	return pc, nil
 }
+
+func (c Config) mergeMappings(pkg map[string]string) map[string]string {
+	mappings := make(map[string]string)
+	for k, v := range c.TypeMappings {
+		mappings[k] = v
+	}
+	for k, v := range pkg {
+		mappings[k] = v
+	}
+	return mappings
+}