diff --git a/packages/react-ghostmaker/src/maybeGhost/asGhost.test.ts b/packages/react-ghostmaker/src/maybeGhost/asGhost.test.ts
new file mode 100644
index 0000000..c5c8f01
--- /dev/null
+++ b/packages/react-ghostmaker/src/maybeGhost/asGhost.test.ts
@@ -0,0 +1,59 @@
+import { asGhostProps } from "../maybeGhost";
+import { isReactGhost } from "../types";
+import { expect, test } from "vitest";
+
+interface Props {
+  first: string;
+  second?: string;
+  third: string | undefined;
+}
+
+test("makes Ghosts of all props", () => {
+  const ghostProps = asGhostProps<Props>({
+    first: "hello",
+    second: "world",
+    third: "!",
+  });
+
+  expect(ghostProps.firstGhost).toSatisfy(isReactGhost);
+  expect(ghostProps.secondGhost).toSatisfy(isReactGhost);
+  expect(ghostProps.thirdGhost).toSatisfy(isReactGhost);
+});
+
+test("does not make Ghosts of explicit undefined", () => {
+  const ghostProps = asGhostProps<Props>({
+    first: "hello",
+    second: undefined,
+    third: "!",
+  });
+
+  expect(ghostProps.firstGhost).toSatisfy(isReactGhost);
+  expect(ghostProps.secondGhost).toBeUndefined();
+  expect(ghostProps.thirdGhost).toSatisfy(isReactGhost);
+});
+
+test("does not make Ghosts of not given props", () => {
+  const ghostProps = asGhostProps<Props>({
+    first: "hello",
+    third: "!",
+  });
+
+  expect(ghostProps.firstGhost).toSatisfy(isReactGhost);
+  expect(ghostProps.secondGhost).toBeUndefined();
+  expect(ghostProps.thirdGhost).toSatisfy(isReactGhost);
+});
+
+test("does not make Ghosts of excluded props", () => {
+  const ghostProps = asGhostProps<Props>(
+    {
+      first: "hello",
+      second: "world",
+      third: "!",
+    },
+    ["first"],
+  );
+
+  expect(ghostProps.firstGhost).toSatisfy(isReactGhost);
+  expect(ghostProps.secondGhost).not.toSatisfy(isReactGhost);
+  expect(ghostProps.thirdGhost).not.toSatisfy(isReactGhost);
+});
diff --git a/packages/react-ghostmaker/src/maybeGhost/asGhost.ts b/packages/react-ghostmaker/src/maybeGhost/asGhost.ts
index c99197d..d223ace 100644
--- a/packages/react-ghostmaker/src/maybeGhost/asGhost.ts
+++ b/packages/react-ghostmaker/src/maybeGhost/asGhost.ts
@@ -20,6 +20,10 @@ export function asGhostProps<T, TProps extends (keyof T)[] = (keyof T)[]>(
   const fixupObjectEntry = (entry: [string, unknown]) => {
     const [key, value] = entry;
 
+    if (value === undefined) {
+      return entry;
+    }
+
     const shouldFixup =
       keys === undefined || keys.includes(key as TProps[number]);
 
@@ -27,7 +31,7 @@ export function asGhostProps<T, TProps extends (keyof T)[] = (keyof T)[]>(
       return [`${key}Ghost`, asGhost(value)];
     }
 
-    return [key, value];
+    return entry;
   };
 
   return Object.fromEntries(