diff --git a/src/microservices/Microservices.IsIdentifiable/Service/IsIdentifiableQueueConsumer.cs b/src/microservices/Microservices.IsIdentifiable/Service/IsIdentifiableQueueConsumer.cs
index 9eae37958..997ccbf9a 100644
--- a/src/microservices/Microservices.IsIdentifiable/Service/IsIdentifiableQueueConsumer.cs
+++ b/src/microservices/Microservices.IsIdentifiable/Service/IsIdentifiableQueueConsumer.cs
@@ -65,8 +65,13 @@ protected override void ProcessMessageImpl(IMessageHeader header, ExtractedFileS
             }
             catch (Exception e)
             {
-                SendVerificationMessage(statusMessage, header, tag, VerifiedFileStatus.ErrorWontRetry, $"Exception while classifying {statusMessage.GetType().Name}:\n{e}. File could not be scanned.");
-                return;
+                if (e is ArithmeticException)
+                {
+                    SendVerificationMessage(statusMessage, header, tag, VerifiedFileStatus.ErrorWontRetry, $"Exception while classifying {statusMessage.GetType().Name}:\n{e}");
+                    return;
+                }
+
+                throw;
             }
 
             foreach (Failure f in failures)
diff --git a/tests/microservices/Microservices.IsIdentifiable.Tests/Service/IsIdentifiableQueueConsumerTests.cs b/tests/microservices/Microservices.IsIdentifiable.Tests/Service/IsIdentifiableQueueConsumerTests.cs
index 6040ddf64..caa304a5d 100644
--- a/tests/microservices/Microservices.IsIdentifiable.Tests/Service/IsIdentifiableQueueConsumerTests.cs
+++ b/tests/microservices/Microservices.IsIdentifiable.Tests/Service/IsIdentifiableQueueConsumerTests.cs
@@ -1,4 +1,4 @@
-using IsIdentifiable.Failures;
+using IsIdentifiable.Failures;
 using IsIdentifiable.Reporting;
 using Microservices.IsIdentifiable.Service;
 using Moq;
@@ -252,6 +252,52 @@ public void ProcessMessage_ClassifierArithmeticException_SendsErrorWontRetry()
             Assert.True(_response.Report.StartsWith("Exception while classifying ExtractedFileStatusMessage:\nSystem.ArithmeticException: divide by zero"));
         }
 
+        [Test]
+        public void ProcessMessage_ClassifierUnhandledException_CallsFatal()
+        {
+            // Arrange
+
+            var mockClassifier = new Mock<IClassifier>(MockBehavior.Strict);
+            mockClassifier.Setup(x => x.Classify(It.IsAny<IFileInfo>())).Throws(new Exception("whee"));
+
+            var consumer = GetNewIsIdentifiableQueueConsumer(null, mockClassifier.Object);
+
+            // Act
+
+            consumer.TestMessage(_extractedFileStatusMessage);
+
+            // Assert
+
+            TestTimelineAwaiter.Await(() => _fatalArgs != null, "Expected Fatal to be called");
+            Assert.AreEqual("ProcessMessageImpl threw unhandled exception", _fatalArgs?.Message);
+            Assert.AreEqual("whee", _fatalArgs?.Exception?.Message);
+            Assert.AreEqual(0, consumer.NackCount);
+            Assert.AreEqual(0, consumer.AckCount);
+        }
+
+        [Test]
+        public void ProcessMessage_ClassifierInvalidFile_CallsFatal()
+        {
+            // Arrange
+
+            var mockClassifier = new Mock<IClassifier>(MockBehavior.Strict);
+            mockClassifier.Setup(x => x.Classify(It.IsAny<IFileInfo>())).Throws(new ApplicationException("File does not contain valid preamble and header"));
+
+            var consumer = GetNewIsIdentifiableQueueConsumer(null, mockClassifier.Object);
+
+            // Act
+
+            consumer.TestMessage(_extractedFileStatusMessage);
+
+            // Assert
+
+            TestTimelineAwaiter.Await(() => _fatalArgs != null, "Expected Fatal to be called");
+            Assert.AreEqual("ProcessMessageImpl threw unhandled exception", _fatalArgs?.Message);
+            Assert.AreEqual("File does not contain valid preamble and header", _fatalArgs?.Exception?.Message);
+            Assert.AreEqual(0, consumer.NackCount);
+            Assert.AreEqual(0, consumer.AckCount);
+        }
+
         #endregion
     }
 }