diff --git a/src/FlexLabs.EntityFrameworkCore.Upsert/UpsertCommandBuilder.cs b/src/FlexLabs.EntityFrameworkCore.Upsert/UpsertCommandBuilder.cs
index d685a3f..15bf2fa 100644
--- a/src/FlexLabs.EntityFrameworkCore.Upsert/UpsertCommandBuilder.cs
+++ b/src/FlexLabs.EntityFrameworkCore.Upsert/UpsertCommandBuilder.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
diff --git a/src/FlexLabs.EntityFrameworkCore.Upsert/UpsertExtensions.cs b/src/FlexLabs.EntityFrameworkCore.Upsert/UpsertExtensions.cs
index 0251ea4..1975950 100644
--- a/src/FlexLabs.EntityFrameworkCore.Upsert/UpsertExtensions.cs
+++ b/src/FlexLabs.EntityFrameworkCore.Upsert/UpsertExtensions.cs
@@ -48,6 +48,7 @@ public static UpsertCommandBuilder<TEntity> UpsertRange<TEntity>(this DbContext
                 throw new ArgumentNullException(nameof(entities));
 
             var entityType = dbContext.GetService<IModel>().FindEntityType(typeof(TEntity))
+                ?? (entities.Length == 0 ? null : dbContext.GetService<IModel>().FindEntityType(entities.First().GetType()))
                 ?? throw new InvalidOperationException(Resources.EntityTypeMustBeMappedInDbContext);
             return new UpsertCommandBuilder<TEntity>(dbContext, entityType, entities);
         }
@@ -67,13 +68,14 @@ public static UpsertCommandBuilder<TEntity> UpsertRange<TEntity>(this DbContext
             if (entities == null)
                 throw new ArgumentNullException(nameof(entities));
 
-            var entityType = dbContext.GetService<IModel>().FindEntityType(typeof(TEntity))
-                ?? throw new InvalidOperationException(Resources.EntityTypeMustBeMappedInDbContext);
             var collection = entities switch
             {
                 ICollection<TEntity> entityCollection => entityCollection,
                 _ => entities.ToArray()
             };
+            var entityType = dbContext.GetService<IModel>().FindEntityType(typeof(TEntity))
+                ?? (collection.Count > 0 ? null : dbContext.GetService<IModel>().FindEntityType(collection.First().GetType()))
+                ?? throw new InvalidOperationException(Resources.EntityTypeMustBeMappedInDbContext);
             return new UpsertCommandBuilder<TEntity>(dbContext, entityType, collection);
         }