diff --git a/bindings/walk/walk.go b/bindings/walk/walk.go
index bb8d7f8..fa6d6e6 100644
--- a/bindings/walk/walk.go
+++ b/bindings/walk/walk.go
@@ -53,7 +53,7 @@ func Walk(v Visitor, node bindings.Node) {
 		Walk(v, n.Type)
 		Walk(v, n.Initializer)
 	case *bindings.ReferenceType:
-		// noop
+		walkList(v, n.Arguments)
 	case *bindings.LiteralKeyword:
 		// noop
 	case *bindings.LiteralType:
diff --git a/convert_test.go b/convert_test.go
index 0f01e74..95e18e8 100644
--- a/convert_test.go
+++ b/convert_test.go
@@ -106,6 +106,8 @@ func TestGeneration(t *testing.T) {
 				muts := strings.Split(strings.TrimSpace(string(mutsCSV)), ",")
 				for _, m := range muts {
 					switch m {
+					case "NotNullMaps":
+						mutations = append(mutations, config.NotNullMaps)
 					case "EnumAsTypes":
 						mutations = append(mutations, config.EnumAsTypes)
 					case "EnumLists":
diff --git a/testdata/enums/enums.go b/testdata/enums/enums.go
index b4a69df..82c7771 100644
--- a/testdata/enums/enums.go
+++ b/testdata/enums/enums.go
@@ -1,4 +1,4 @@
-package codersdk
+package enums
 
 type (
 	EnumString    string
diff --git a/testdata/enums/enums.ts b/testdata/enums/enums.ts
index 819fa79..63a40e7 100644
--- a/testdata/enums/enums.ts
+++ b/testdata/enums/enums.ts
@@ -1,22 +1,22 @@
 // Code generated by 'guts'. DO NOT EDIT.
 
-// From codersdk/enums.go
+// From enums/enums.go
 export enum Audience {
     Team = "team",
     Tenant = "tenant",
     World = "world"
 }
 
-// From codersdk/enums.go
+// From enums/enums.go
 export enum EnumInt {
     EnumNumBar = 10,
     EnumNumFoo = 5
 }
 
-// From codersdk/enums.go
+// From enums/enums.go
 export type EnumSliceType = readonly EnumString[];
 
-// From codersdk/enums.go
+// From enums/enums.go
 export enum EnumString {
     EnumBar = "bar",
     EnumBaz = "baz",
diff --git a/testdata/enumtypes/enumtypes.go b/testdata/enumtypes/enumtypes.go
index b4a69df..d13ec85 100644
--- a/testdata/enumtypes/enumtypes.go
+++ b/testdata/enumtypes/enumtypes.go
@@ -1,4 +1,4 @@
-package codersdk
+package enumtypes
 
 type (
 	EnumString    string
diff --git a/testdata/enumtypes/enumtypes.ts b/testdata/enumtypes/enumtypes.ts
index 7392a61..cfe2902 100644
--- a/testdata/enumtypes/enumtypes.ts
+++ b/testdata/enumtypes/enumtypes.ts
@@ -1,19 +1,19 @@
 // Code generated by 'guts'. DO NOT EDIT.
 
-// From codersdk/enumtypes.go
+// From enumtypes/enumtypes.go
 export type Audience = "team" | "tenant" | "world";
 
 export const Audiences: Audience[] = ["team", "tenant", "world"];
 
-// From codersdk/enumtypes.go
+// From enumtypes/enumtypes.go
 export type EnumInt = 10 | 5;
 
 export const EnumInts: EnumInt[] = [10, 5];
 
-// From codersdk/enumtypes.go
+// From enumtypes/enumtypes.go
 export type EnumSliceType = readonly EnumString[];
 
-// From codersdk/enumtypes.go
+// From enumtypes/enumtypes.go
 export type EnumString = "bar" | "baz" | "foo" | "qux";
 
 export const EnumStrings: EnumString[] = ["bar", "baz", "foo", "qux"];
diff --git a/testdata/notnullmap/mutations b/testdata/notnullmap/mutations
new file mode 100644
index 0000000..8f833da
--- /dev/null
+++ b/testdata/notnullmap/mutations
@@ -0,0 +1 @@
+NotNullMaps
\ No newline at end of file
diff --git a/testdata/notnullmap/notnullmap.go b/testdata/notnullmap/notnullmap.go
new file mode 100644
index 0000000..1957d8e
--- /dev/null
+++ b/testdata/notnullmap/notnullmap.go
@@ -0,0 +1,10 @@
+package notnullmap
+
+type Foo struct {
+	Bar    map[string]bool
+	Nested GenericFoo[map[string]int]
+}
+
+type GenericFoo[T any] struct {
+	Bar T
+}
diff --git a/testdata/notnullmap/notnullmap.ts b/testdata/notnullmap/notnullmap.ts
new file mode 100644
index 0000000..559b127
--- /dev/null
+++ b/testdata/notnullmap/notnullmap.ts
@@ -0,0 +1,12 @@
+// Code generated by 'guts'. DO NOT EDIT.
+
+// From notnullmap/notnullmap.go
+interface Foo {
+    Bar: Record<string, boolean>;
+    Nested: GenericFoo<Record<string, number>>;
+}
+
+// From notnullmap/notnullmap.go
+interface GenericFoo<T extends any> {
+    Bar: T;
+}