diff --git a/type-generation/src/astToIR.ts b/type-generation/src/astToIR.ts
index 78cd17a..ced1193 100644
--- a/type-generation/src/astToIR.ts
+++ b/type-generation/src/astToIR.ts
@@ -15,6 +15,7 @@ import {
   SourceFile,
   SyntaxKind,
   ts,
+  TypeElementMemberedNode,
   TypeElementTypes,
   TypeLiteralNode,
   TypeNode,
@@ -365,9 +366,15 @@ class SyntheticTypeConverter {
   }
 
   doConversion(
-    nodes: Pick<TypeLiteralNode, "getMembers">[],
+    nodes: (TypeElementMemberedNode & Node)[],
     modifiers: Modifier,
   ): ReferenceTypeIR {
+    const res = nodes.filter(
+      (x): x is TypeElementMemberedNode & TypeParameteredNode & Node =>
+        Node.isTypeParametered(x),
+    );
+    const typeParams = this.converter.getTypeParamsFromDecls(res);
+
     let name = this.nameContext.join("__");
     if (!name.endsWith("_iface")) {
       name += "_iface";
@@ -384,7 +391,14 @@ class SyntheticTypeConverter {
         (x) => !Node.isPropertyNamed(x) || pickSet.has(x.getName()),
       );
     }
-    const result = this.converter.interfaceToIR(name, [], members, [], [], []);
+    const result = this.converter.interfaceToIR(
+      name,
+      [],
+      members,
+      [],
+      [],
+      typeParams,
+    );
     if (partial) {
       for (const prop of result.properties) {
         prop.isOptional = true;
@@ -501,10 +515,6 @@ class SyntheticTypeConverter {
       }
       if (res.kind === "interfaces") {
         const { name, ifaces } = res;
-        const typeParams = this.converter.getTypeParamsFromDecls(ifaces);
-        if (typeParams.length > 0) {
-          throw new Error("Not handled");
-        }
         this.nameContext.push(name);
         const result = this.doConversion(ifaces, modifiers);
         this.nameContext.pop();
diff --git a/type-generation/tests/a.test.ts b/type-generation/tests/a.test.ts
index a38de89..d670ad0 100644
--- a/type-generation/tests/a.test.ts
+++ b/type-generation/tests/a.test.ts
@@ -1787,6 +1787,24 @@ describe("emit", () => {
           `).trim(),
         );
       });
+      it("PartialTypeArg", () => {
+        const res = emitFile(`
+          interface A<T> { a: T; }
+          type D = Partial<A<string>>;
+          declare function f(): D;
+        `);
+        assert.strictEqual(
+          removeTypeIgnores(res.slice(1).join("\n\n")),
+          dedent(`
+            type D = D__Partial__A_iface
+
+            def f() -> D: ...
+
+            class D__Partial__A_iface[T](Protocol):
+                a: T | None = ...
+          `).trim(),
+        );
+      });
     });
     it("Composed type operators", () => {
       const res = emitFile(`