diff --git a/DOCUMENTATION.md b/DOCUMENTATION.md
index f95f4ca9..beb3700b 100644
--- a/DOCUMENTATION.md
+++ b/DOCUMENTATION.md
@@ -4194,7 +4194,7 @@ The name must be a string; the optional doc argument can have any type.
     "start_timestamp": str,
     "end_timestamp": str,
     "push_timestamp": str,
-    "image_size": int,
+    "image_size": str,
     "dockerfile": str,
     "error_message": str,
     "is_a_build_of__service": Union[List[ServiceType], PineDeferred],
diff --git a/balena/types/models.py b/balena/types/models.py
index 1a06590c..0df4ccbf 100644
--- a/balena/types/models.py
+++ b/balena/types/models.py
@@ -432,7 +432,7 @@ class ImageType(TypedDict):
     start_timestamp: str
     end_timestamp: str
     push_timestamp: str
-    image_size: int
+    image_size: str
     dockerfile: str
     error_message: str
     is_a_build_of__service: NavigationResource["ServiceType"]