diff --git a/Dapper/SqlMapper.cs b/Dapper/SqlMapper.cs
index dbbb42557f0077bb05faed01fc536c47e61f607f..a48a460f2629a00335084970760696976e4f2215 100644
--- a/Dapper/SqlMapper.cs
+++ b/Dapper/SqlMapper.cs
@@ -431,9 +431,12 @@ public static IEnumerable<T> Query<T>(this IDbConnection cnn, string sql, object
             }
 
             // nice and simple
-            identity = new Identity(sql, commandType, cnn, null, (object)param == null ? null : ((object)param).GetType(), null);
-            info = GetCacheInfo(identity);
-            return ExecuteCommand(cnn, transaction, sql, info.ParamReader, (object)param, commandTimeout, commandType);
+            if ((object)param != null)
+            {
+                identity = new Identity(sql, commandType, cnn, null, (object) param == null ? null : ((object) param).GetType(), null);
+                info = GetCacheInfo(identity);
+            }
+            return ExecuteCommand(cnn, transaction, sql, (object)param == null ? null : info.ParamReader, (object)param, commandTimeout, commandType);
         }
 #if !CSHARP30
         /// <summary>