diff --git a/src/index.ts b/src/index.ts
index 22f9a7c..83d0fb9 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -140,13 +140,14 @@ class Schema {
       let value = source[z];
       arr.forEach(r => {
         let rule: InternalRuleItem = r;
+        let inferredType: RuleType;
         if (typeof rule.transform === 'function') {
           if (source === source_) {
             source = { ...source };
           }
           value = source[z] = rule.transform(value);
           if (value !== undefined && value !== null) {
-            rule.type = rule.type || ((Array.isArray(value) ? 'array' : typeof value) as RuleType);
+            inferredType = (Array.isArray(value) ? 'array' : typeof value) as RuleType;
           }
         }
         if (typeof rule === 'function') {
@@ -155,6 +156,9 @@ class Schema {
           };
         } else {
           rule = { ...rule };
+          if (inferredType) {
+            rule.type = rule.type || inferredType;
+          }
         }
 
         // Fill validator. Skip if nothing need to validate
diff --git a/tests/number.spec.ts b/tests/number.spec.ts
index fbb54e4..0aa32e5 100644
--- a/tests/number.spec.ts
+++ b/tests/number.spec.ts
@@ -148,6 +148,14 @@ describe('number', () => {
         done();
       });
   });
+  it('reinfers transformed type across validations', async () => {
+    const schema = new Schema({
+      v: { required: true, transform: value => value },
+    });
+
+    await expect(schema.validate({ v: 1 })).resolves.toEqual({ v: 1 });
+    await expect(schema.validate({ v: 'value' })).resolves.toEqual({ v: 'value' });
+  });
   it('transform array', done => {
     const value = { v: [0, 1] };
     new Schema({