diff --git a/types/natural-compare-lite/tsconfig.json b/types/natural-compare-lite/tsconfig.json
index e3ed3ac1e0..ddfcb244cb 100644
--- a/types/natural-compare-lite/tsconfig.json
+++ b/types/natural-compare-lite/tsconfig.json
@@ -6,7 +6,7 @@
         ],
         "noImplicitAny": true,
         "noImplicitThis": true,
-        "strictNullChecks": false,
+        "strictNullChecks": true,
         "strictFunctionTypes": true,
         "baseUrl": "../",
         "typeRoots": [
diff --git a/types/natural-compare/tsconfig.json b/types/natural-compare/tsconfig.json
index 81322d5590..c8af37bb22 100644
--- a/types/natural-compare/tsconfig.json
+++ b/types/natural-compare/tsconfig.json
@@ -6,7 +6,7 @@
         ],
         "noImplicitAny": true,
         "noImplicitThis": true,
-        "strictNullChecks": false,
+        "strictNullChecks": true,
         "strictFunctionTypes": true,
         "baseUrl": "../",
         "typeRoots": [