diff --git a/CoreIntegrationTests/Infrastructure/MongoDbDocumentTestBase.cs b/CoreIntegrationTests/Infrastructure/MongoDbDocumentTestBase.cs
index 0c333a9..a1f3944 100644
--- a/CoreIntegrationTests/Infrastructure/MongoDbDocumentTestBase.cs
+++ b/CoreIntegrationTests/Infrastructure/MongoDbDocumentTestBase.cs
@@ -1078,7 +1078,7 @@ namespace CoreIntegrationTests.Infrastructure
         #region Math
 
         [Fact]
-        public async Task SumByAsync()
+        public async Task SumByDecimalAsync()
         {
             // Arrange
             var criteria = $"{GetTestName()}.{DocumentTypeName}.{Guid.NewGuid()}";
@@ -1100,6 +1100,29 @@ namespace CoreIntegrationTests.Infrastructure
             Assert.Equal(expectedSum, result);
         }
 
+        [Fact]
+        public void SumByDecimal()
+        {
+            // Arrange
+            var criteria = $"{GetTestName()}.{DocumentTypeName}.{Guid.NewGuid()}";
+            var documents = CreateTestDocuments(5);
+            var i = 1;
+            documents.ForEach(e =>
+            {
+                e.Nested.SomeDate = e.Nested.SomeDate.AddDays(i++);
+                e.Nested.SomeAmount = 5m;
+                e.SomeContent = criteria;
+            });
+            SUT.AddMany<T>(documents);
+            var expectedSum = documents.Sum(e => e.Nested.SomeAmount);
+
+            // Act
+            var result = SUT.SumBy<T>(e => e.SomeContent == criteria, e => e.Nested.SomeAmount, PartitionKey);
+
+            // Assert
+            Assert.Equal(expectedSum, result);
+        }
+
         #endregion Math
 
         #region Test Utils
diff --git a/CoreIntegrationTests/Infrastructure/MongoDbTKeyDocumentTestBase.cs b/CoreIntegrationTests/Infrastructure/MongoDbTKeyDocumentTestBase.cs
index e4f2051..e4b0843 100644
--- a/CoreIntegrationTests/Infrastructure/MongoDbTKeyDocumentTestBase.cs
+++ b/CoreIntegrationTests/Infrastructure/MongoDbTKeyDocumentTestBase.cs
@@ -1071,7 +1071,7 @@ namespace CoreIntegrationTests.Infrastructure
         #region Math
 
         [Fact]
-        public async Task SumByAsync()
+        public async Task SumByDecimalAsync()
         {
             // Arrange
             var criteria = $"{GetTestName()}.{DocumentTypeName}.{Guid.NewGuid()}";
@@ -1093,6 +1093,29 @@ namespace CoreIntegrationTests.Infrastructure
             Assert.Equal(expectedSum, result);
         }
 
+        [Fact]
+        public void SumByDecimal()
+        {
+            // Arrange
+            var criteria = $"{GetTestName()}.{DocumentTypeName}.{Guid.NewGuid()}";
+            var documents = CreateTestDocuments(5);
+            var i = 1;
+            documents.ForEach(e =>
+            {
+                e.Nested.SomeDate = e.Nested.SomeDate.AddDays(i++);
+                e.Nested.SomeAmount = 5m;
+                e.SomeContent = criteria;
+            });
+            SUT.AddMany<T, TKey>(documents);
+            var expectedSum = documents.Sum(e => e.Nested.SomeAmount);
+
+            // Act
+            var result = SUT.SumBy<T, TKey>(e => e.SomeContent == criteria, e => e.Nested.SomeAmount, PartitionKey);
+
+            // Assert
+            Assert.Equal(expectedSum, result);
+        }
+
         #endregion Math
 
         #region Test Utils