diff --git a/invokeai/backend/model_management/memory_snapshot.py b/invokeai/backend/model_management/memory_snapshot.py
index 01f1328114..fe54af191c 100644
--- a/invokeai/backend/model_management/memory_snapshot.py
+++ b/invokeai/backend/model_management/memory_snapshot.py
@@ -64,7 +64,7 @@ class MemorySnapshot:
         return cls(process_ram, vram, malloc_info)
 
 
-def get_pretty_snapshot_diff(snapshot_1: MemorySnapshot, snapshot_2: MemorySnapshot) -> str:
+def get_pretty_snapshot_diff(snapshot_1: Optional[MemorySnapshot], snapshot_2: Optional[MemorySnapshot]) -> str:
     """Get a pretty string describing the difference between two `MemorySnapshot`s."""
 
     def get_msg_line(prefix: str, val1: int, val2: int):
@@ -73,6 +73,9 @@ def get_pretty_snapshot_diff(snapshot_1: MemorySnapshot, snapshot_2: MemorySnaps
 
     msg = ""
 
+    if snapshot_1 is None or snapshot_2 is None:
+        return msg
+
     msg += get_msg_line("Process RAM", snapshot_1.process_ram, snapshot_2.process_ram)
 
     if snapshot_1.malloc_info is not None and snapshot_2.malloc_info is not None:
diff --git a/tests/backend/model_management/test_memory_snapshot.py b/tests/backend/model_management/test_memory_snapshot.py
index 80aed7b7ba..dcbb173e96 100644
--- a/tests/backend/model_management/test_memory_snapshot.py
+++ b/tests/backend/model_management/test_memory_snapshot.py
@@ -17,6 +17,7 @@ snapshots = [
     MemorySnapshot(process_ram=1.0, vram=2.0, malloc_info=None),
     MemorySnapshot(process_ram=1.0, vram=None, malloc_info=Struct_mallinfo2()),
     MemorySnapshot(process_ram=1.0, vram=None, malloc_info=None),
+    None,
 ]
 
 
@@ -26,10 +27,12 @@ def test_get_pretty_snapshot_diff(snapshot_1, snapshot_2):
     """Test that get_pretty_snapshot_diff() works with various combinations of missing MemorySnapshot fields."""
     msg = get_pretty_snapshot_diff(snapshot_1, snapshot_2)
 
-    expected_lines = 1
-    if snapshot_1.vram is not None and snapshot_2.vram is not None:
+    expected_lines = 0
+    if snapshot_1 is not None and snapshot_2 is not None:
         expected_lines += 1
-    if snapshot_1.malloc_info is not None and snapshot_2.malloc_info is not None:
-        expected_lines += 5
+        if snapshot_1.vram is not None and snapshot_2.vram is not None:
+            expected_lines += 1
+        if snapshot_1.malloc_info is not None and snapshot_2.malloc_info is not None:
+            expected_lines += 5
 
     assert len(msg.splitlines()) == expected_lines