diff --git a/.changeset/swift-swans-rush.md b/.changeset/swift-swans-rush.md
new file mode 100644
index 00000000..918fa76e
--- /dev/null
+++ b/.changeset/swift-swans-rush.md
@@ -0,0 +1,5 @@
+---
+"@proofkit/fmdapi": patch
+---
+
+Update removeFMTableNames function for proper type-safety
diff --git a/packages/fmdapi/src/utils.ts b/packages/fmdapi/src/utils.ts
index 093dc5e6..f5345415 100644
--- a/packages/fmdapi/src/utils.ts
+++ b/packages/fmdapi/src/utils.ts
@@ -1,31 +1,29 @@
-import type { S, L, U } from "ts-toolbelt";
 import type * as z3 from "zod/v3";
 import type * as z4 from "zod/v4/core";
 
-// eslint-disable-next-line @typescript-eslint/no-explicit-any
-type TransformedFields<T extends Record<string, any>> = U.Merge<
-  {
-    [Field in keyof T]: {
-      [Key in Field extends string
-        ? L.Last<S.Split<Field, "::">>
-        : Field]: T[Field];
-    };
-  }[keyof T]
->;
+type StripFMTableName<K extends PropertyKey> = K extends `${string}::${infer R}`
+  ? R
+  : K;
 
-// eslint-disable-next-line @typescript-eslint/no-explicit-any
-export function removeFMTableNames<T extends Record<string, any>>(
+type TransformedFields<T extends object> = {
+  [K in keyof T as K extends string ? StripFMTableName<K> : K]: T[K];
+};
+
+export function removeFMTableNames<T extends object>(
   obj: T,
 ): TransformedFields<T> {
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  const newObj: any = {};
+  const newObj = {} as TransformedFields<T>;
   for (const key in obj) {
-    if (key.includes("::")) {
-      const newKey = key.split("::")[1];
-      newObj[newKey as keyof TransformedFields<T>] = obj[key];
-    } else {
-      newObj[key] = obj[key];
-    }
+    const originalKey = key as keyof T;
+    const value = obj[originalKey];
+    const mappedKey = (
+      typeof key === "string" && key.includes("::") ? key.split("::")[1] : key
+    ) as keyof TransformedFields<T>;
+
+    // Use a temporary index signature cast to assign without any
+    (newObj as unknown as Record<PropertyKey, unknown>)[
+      mappedKey as unknown as PropertyKey
+    ] = value as unknown;
   }
   return newObj;
 }
diff --git a/packages/fmdapi/tests/removeFMTableNames.test.ts b/packages/fmdapi/tests/removeFMTableNames.test.ts
new file mode 100644
index 00000000..1bfe3e7f
--- /dev/null
+++ b/packages/fmdapi/tests/removeFMTableNames.test.ts
@@ -0,0 +1,50 @@
+import { describe, expect, it } from "vitest";
+import { removeFMTableNames } from "../src";
+
+describe("removeFMTableNames", () => {
+  it("strips FM table prefixes from keys and preserves values", () => {
+    const input = {
+      "Customer::name": "Alice",
+      count: 2,
+      "X::flag": true,
+    } as const;
+
+    const out = removeFMTableNames(input);
+
+    expect(out).toEqual({ name: "Alice", count: 2, flag: true });
+    expect("Customer::name" in (out as Record<string, unknown>)).toBe(false);
+    expect("name" in out).toBe(true);
+    expect(out.name).toBe("Alice");
+    expect(out.count).toBe(2);
+    expect(out.flag).toBe(true);
+  });
+
+  it("produces a type with stripped keys", () => {
+    type Input = {
+      "Customer::first_name": string;
+      last_name: string;
+      "Portal::recordId": number;
+    };
+
+    const input: Input = {
+      "Customer::first_name": "Bob",
+      last_name: "Builder",
+      "Portal::recordId": 42,
+    };
+    const out = removeFMTableNames(input);
+
+    // Type-level assertions via assignment
+    const first: string = out.first_name;
+    const last: string = out.last_name;
+    const recId: number = out.recordId;
+    expect(first).toBe("Bob");
+    expect(last).toBe("Builder");
+    expect(recId).toBe(42);
+
+    // Old keys should not exist on the resulting type
+    // @ts-expect-error - old FM-prefixed key should not exist on result type
+    out["Customer::first_name"];
+    // @ts-expect-error - old FM-prefixed key should not exist on result type
+    out["Portal::recordId"];
+  });
+});
diff --git a/packages/fmdapi/tests/tsconfig.json b/packages/fmdapi/tests/tsconfig.json
new file mode 100644
index 00000000..f4d49859
--- /dev/null
+++ b/packages/fmdapi/tests/tsconfig.json
@@ -0,0 +1,10 @@
+{
+  "extends": "../tsconfig.json",
+  "compilerOptions": {
+    "noEmit": true,
+    "types": ["vitest", "node"],
+    "isolatedModules": true
+  },
+  "include": ["./**/*.ts"],
+  "exclude": ["../dist", "../schema"]
+}
diff --git a/packages/fmdapi/tests/tsconfig.typecheck.json b/packages/fmdapi/tests/tsconfig.typecheck.json
new file mode 100644
index 00000000..16f5563e
--- /dev/null
+++ b/packages/fmdapi/tests/tsconfig.typecheck.json
@@ -0,0 +1,14 @@
+{
+  "compilerOptions": {
+    "strict": true,
+    "target": "ES2022",
+    "module": "ESNext",
+    "moduleResolution": "Bundler",
+    "jsx": "react-jsx",
+    "skipLibCheck": true,
+    "noEmit": true,
+    "isolatedModules": true,
+    "types": ["node"]
+  },
+  "files": ["./type/removeFMTableNames.typecheck.ts"]
+}