diff --git a/package.json b/package.json
index f3572aa..bbdb923 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@pomle/paths",
-  "version": "1.5.1",
+  "version": "1.5.2",
   "description": "TypeScript library for handling type safe and type rich paths and query params",
   "author": "Pontus Alexander <pontus.alexander@gmail.com>",
   "license": "MIT",
diff --git a/src/__tests__/query.test.ts b/src/__tests__/query.test.ts
index 4307b14..f7d2b08 100644
--- a/src/__tests__/query.test.ts
+++ b/src/__tests__/query.test.ts
@@ -60,6 +60,16 @@ describe('#createQuery', () => {
       );
     });
 
+    it('handles explicit undefined gracefully where partials are allowed', () => {
+      expect(
+        query.build({ boolean: [true, false], text: undefined }),
+      ).toStrictEqual('boolean=1&boolean=0');
+
+      expect(query.build({ boolean: [true, false] })).toStrictEqual(
+        'boolean=1&boolean=0',
+      );
+    });
+
     it('creates typed params from URL', () => {
       expect(
         query.parse(
diff --git a/src/query.ts b/src/query.ts
index c0c28b4..264574c 100644
--- a/src/query.ts
+++ b/src/query.ts
@@ -52,7 +52,9 @@ export function createQuery<T extends QueryCodec>(codecs: T): Query<T> {
   function encode(values: Values<T>) {
     const params: Record<string, string[]> = {};
     for (const key of keys) {
-      params[key] = values[key].map(codecs[key].encode);
+      if (Array.isArray(values[key])) {
+        params[key] = values[key].map(codecs[key].encode);
+      }
     }
     return params as Params<T>;
   }