diff --git a/my-types.d.ts b/my-types.d.ts
new file mode 100644
index 00000000..96a33e2a
--- /dev/null
+++ b/my-types.d.ts
@@ -0,0 +1,3 @@
+type SafeArray<T> = Omit<Array<T>, number> & {
+  readonly [index: number]: T | undefined;
+};
diff --git a/src/replicache/utils.ts b/src/replicache/utils.ts
index d4a4c618..baba44f0 100644
--- a/src/replicache/utils.ts
+++ b/src/replicache/utils.ts
@@ -69,7 +69,7 @@ export const scanIndexLocal = (initialFacts: Fact<any>[]) => ({
   eav<A extends Attribute>(entity: string, attribute: A) {
     return initialFacts.filter(
       (f) => f.entity === entity && f.attribute === attribute,
-    ) as Fact<A>[];
+    ) as SafeArray<Fact<A>>;
   },
 });
 
diff --git a/tsconfig.json b/tsconfig.json
index c1a11c79..23ebaecd 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,13 +1,7 @@
 {
   "compilerOptions": {
-    "lib": [
-      "dom",
-      "dom.iterable",
-      "esnext"
-    ],
-    "types": [
-      "@cloudflare/workers-types"
-    ],
+    "lib": ["dom", "dom.iterable", "esnext"],
+    "types": ["@cloudflare/workers-types"],
     "baseUrl": ".",
     "allowJs": true,
     "skipLibCheck": true,
@@ -30,6 +24,7 @@
     "target": "ES2017"
   },
   "include": [
+    "my-types.d.ts",
     "next-env.d.ts",
     ".next/types/**/*.ts",
     "**/*.js",
@@ -37,7 +32,5 @@
     "**/*.tsx",
     "**/*.mdx"
   ],
-  "exclude": [
-    "node_modules"
-  ]
+  "exclude": ["node_modules"]
 }