diff --git a/Dapper/SqlMapper.cs b/Dapper/SqlMapper.cs
index 563280d2013af211362f7e9ae8e2ac8976d6de59..5c3b10bc187d1fbe0d5337ebf1f814fe00b05d00 100644
--- a/Dapper/SqlMapper.cs
+++ b/Dapper/SqlMapper.cs
@@ -187,6 +187,12 @@ static SqlMapper()
         private static DbType LookupDbType(Type type)
         {
             DbType dbType;
+            var nullUnderlyingType = Nullable.GetUnderlyingType(type);
+            if (nullUnderlyingType != null) type = nullUnderlyingType;
+            if (type.IsEnum)
+            {
+                type = Enum.GetUnderlyingType(type);
+            }
             if (typeMap.TryGetValue(type.TypeHandle, out dbType))
             {
                 return dbType;
@@ -197,6 +203,7 @@ private static DbType LookupDbType(Type type)
                 return DbType.Xml;
             }
 
+
             throw new NotSupportedException(string.Format("The type : {0} is not supported by dapper", type));
         }
 
diff --git a/Tests/Tests.cs b/Tests/Tests.cs
index 25e42f2559f8d218b1f87064d9cf096366315280..8af9cd0ec5bc3c409b374114253c46e6ef11efdc 100644
--- a/Tests/Tests.cs
+++ b/Tests/Tests.cs
@@ -97,6 +97,27 @@ public void TestStrings()
                 .IsSequenceEqualTo(new[] { "a", "b" });
         }
 
+        enum EnumParam : short
+        {
+            None, A, B
+        }
+        class EnumParamObject
+        {
+            public EnumParam A { get; set; }
+            public EnumParam? B { get; set; }
+            public EnumParam? C { get; set; }
+        }
+        public void TestEnumParams()
+        {
+            EnumParam a = EnumParam.A;
+            EnumParam? b = EnumParam.B, c = null;
+            var obj = connection.Query<EnumParamObject>("select @a as A, @b as B, @c as C",
+                new { a, b, c }).Single();
+            obj.A.IsEqualTo(EnumParam.A);
+            obj.B.IsEqualTo(EnumParam.B);
+            obj.C.IsEqualTo(null);
+        }
+
         public class Dog
         {
             public int? Age { get; set; }