diff --git a/src/boolean/all.js b/src/boolean/all.js
index f133295..443a8fa 100644
--- a/src/boolean/all.js
+++ b/src/boolean/all.js
@@ -1 +1,2 @@
 export * as typeDefinition from './BooleanT.js'
+export * as type from './type.js'
diff --git a/src/number/__test__/type.spec.js b/src/number/__test__/type.spec.js
index 9d05744..bd07690 100644
--- a/src/number/__test__/type.spec.js
+++ b/src/number/__test__/type.spec.js
@@ -4,7 +4,9 @@ import math from '#nanomath'
 describe('number type operations', () => {
    it('converts to number', () => {
       assert.strictEqual(math.number(2.637), 2.637)
+      assert(isNaN(math.number(NaN)))
       assert.strictEqual(math.number(true), 1)
       assert.strictEqual(math.number(false), 0)
+      assert.strictEqual(math.number(), 0)
    })
 })
diff --git a/src/number/type.js b/src/number/type.js
index b970b5e..b7656ba 100644
--- a/src/number/type.js
+++ b/src/number/type.js
@@ -3,5 +3,10 @@ import {BooleanT} from '#boolean/BooleanT.js'
 import {Returns} from '#core/Type.js'
 import {NumberT} from '#number/NumberT.js'
 
+const num = f => Returns(NumberT, f)
+
 export const number = plain(a => a)
-number.also(BooleanT, Returns(NumberT, a => a ? 1 : 0))
+number.also(
+   BooleanT, num(a => a ? 1 : 0),
+   [], num(() => 0)
+)