diff --git a/CHANGES.txt b/CHANGES.txt
index d6dd359d98..cfc0a9aace 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -13,6 +13,7 @@ Merged from 4.0:
 Merged from 3.11:
  * Fix NPE when using udfContext in UDF after a restart of a node (CASSANDRA-18739)
 Merged from 3.0:
+ * Make alternation of a user type validate the same way as creation of a user type does (CASSANDRA-18585)
  * Fix missing speculative retries in tablestats (CASSANDRA-18767)
  * Fix Requires for Java for RPM package (CASSANDRA-18751)
  * Fix CQLSH online help topic link (CASSANDRA-17534)
diff --git a/src/java/org/apache/cassandra/cql3/statements/schema/AlterTypeStatement.java b/src/java/org/apache/cassandra/cql3/statements/schema/AlterTypeStatement.java
index 00fbf60fef..40bca4aac9 100644
--- a/src/java/org/apache/cassandra/cql3/statements/schema/AlterTypeStatement.java
+++ b/src/java/org/apache/cassandra/cql3/statements/schema/AlterTypeStatement.java
@@ -127,6 +127,12 @@ public abstract class AlterTypeStatement extends AlterSchemaStatement
 
         UserType apply(KeyspaceMetadata keyspace, UserType userType)
         {
+            if (type.isCounter())
+                throw ire("A user type cannot contain counters");
+
+            if (type.isUDT() && !type.isFrozen())
+                throw ire("A user type cannot contain non-frozen UDTs");
+
             if (userType.fieldPosition(fieldName) >= 0)
             {
                 if (!ifFieldNotExists)
diff --git a/test/unit/org/apache/cassandra/cql3/validation/entities/UserTypesTest.java b/test/unit/org/apache/cassandra/cql3/validation/entities/UserTypesTest.java
index 0d99494979..9ad6aeb047 100644
--- a/test/unit/org/apache/cassandra/cql3/validation/entities/UserTypesTest.java
+++ b/test/unit/org/apache/cassandra/cql3/validation/entities/UserTypesTest.java
@@ -136,6 +136,10 @@ public class UserTypesTest extends CQLTester
         assertInvalidMessage("A user type cannot contain non-frozen UDTs",
                 "CREATE TYPE " + KEYSPACE + ".wrong (a int, b " + myType + ")");
 
+        String ut1 = createType(KEYSPACE, "CREATE TYPE %s (a int)");
+        assertInvalidMessage("A user type cannot contain non-frozen UDTs",
+                "ALTER TYPE " + KEYSPACE + "." + ut1 + " ADD b " + myType);
+
         // referencing a UDT in another keyspace
         assertInvalidMessage("Statement on keyspace " + KEYSPACE + " cannot refer to a user type in keyspace otherkeyspace;" +
                              " user types can only be used in the keyspace they are defined in",
@@ -530,6 +534,20 @@ public class UserTypesTest extends CQLTester
         execute("SELECT addresses FROM %s WHERE id = ? ", userID_1);
     }
 
+    @Test
+    public void testCreateTypeWithUndesiredFieldType() throws Throwable
+    {
+        String typeName = createTypeName();
+        assertInvalidMessage("A user type cannot contain counters", "CREATE TYPE " + typeWithKs(typeName) + " (f counter)");
+    }
+
+    @Test
+    public void testAlterTypeWithUndesiredFieldType() throws Throwable
+    {
+        String typeName = createType("CREATE TYPE %s (a int)");
+        assertInvalidMessage("A user type cannot contain counters", "ALTER TYPE " + typeWithKs(typeName) + " ADD f counter");
+    }
+
     /**
      * Test user type test that does a little more nesting,
      * migrated from cql_tests.py:TestCQL.more_user_types_test()