diff --git a/SqlMapper.cs b/SqlMapper.cs
index 5fef6de7..faa46f93 100644
--- a/SqlMapper.cs
+++ b/SqlMapper.cs
@@ -269,13 +269,19 @@ namespace SqlMapper
 
                         var list = info.Val as IEnumerable;
                         var count = 0;
+                        bool isString = info.Val is IEnumerable<string>;
 
                         if (list != null)
                         {
                             foreach (var item in list)
                             {
                                 count++;
-                                cmd.Parameters.Add(new SqlParameter("@" + info.Name + count, item));
+                                var sqlParam = new SqlParameter("@" + info.Name + count, item);
+                                if (isString)
+                                {
+                                    sqlParam.Size = 4000;
+                                }
+                                cmd.Parameters.Add(sqlParam);
                             }
 
                             cmd.CommandText = cmd.CommandText.Replace("@" + info.Name,
diff --git a/Tests.cs b/Tests.cs
index 1490bc5d..0b8b073f 100644
--- a/Tests.cs
+++ b/Tests.cs
@@ -89,15 +89,19 @@ namespace SqlMapper
             public int IgnoredProperty { get { return 1; } }
         }
 
-        public void TestIntSupportsNull()
+        public void TestStrongType()
         {
-            var dog = connection.ExecuteMapperQuery<Dog>("select Age = @Age", new { Age = (int?)null });
+            var guid = Guid.NewGuid();
+            var dog = connection.ExecuteMapperQuery<Dog>("select Age = @Age, Id = @Id", new { Age = (int?)null, Id = guid });
             
             dog.Count()
                 .IsEquals(1);
 
             dog.First().Age
                 .IsNull();
+
+            dog.First().Id
+                .IsEquals(guid);
         }
 
         public void TestExpando()