diff --git a/tools/project.py b/tools/project.py
index 3066ebe..639f5a1 100644
--- a/tools/project.py
+++ b/tools/project.py
@@ -1236,14 +1236,19 @@ def generate_objdiff_config(
             "target_path": obj_path,
             "metadata": {
                 "auto_generated": build_obj["autogenerated"],
+                "progress_categories": progress_categories,
             },
         }
 
         obj = objects.get(obj_name)
-        if obj is None or not obj.src_path or not obj.src_path.exists():
+        if obj is None:
             objdiff_config["units"].append(unit_config)
             return
 
+        src_exists = obj.src_path is not None and obj.src_path.exists()
+        if src_exists:
+            unit_config["base_path"] = obj.src_obj_path
+
         cflags = obj.options["cflags"]
         reverse_fn_order = False
         if type(cflags) is list:
@@ -1263,12 +1268,14 @@ def generate_objdiff_config(
             cflags = list(filter(keep_flag, cflags))
 
             # Add appropriate lang flag
-            if obj.src_path.suffix in (".cp", ".cpp"):
-                cflags.insert(0, "-lang=c++")
-            else:
-                cflags.insert(0, "-lang=c")
+            if obj.src_path is not None and not any(
+                flag.startswith("-lang") for flag in cflags
+            ):
+                if obj.src_path.suffix in (".cp", ".cpp"):
+                    cflags.insert(0, "-lang=c++")
+                else:
+                    cflags.insert(0, "-lang=c")
 
-        unit_config["base_path"] = obj.src_obj_path
         compiler_version = COMPILER_MAP.get(obj.options["mw_version"])
         if compiler_version is None:
             print(f"Missing scratch compiler mapping for {obj.options['mw_version']}")
@@ -1281,20 +1288,27 @@ def generate_objdiff_config(
                 "platform": "gc_wii",
                 "compiler": compiler_version,
                 "c_flags": cflags_str,
-                "ctx_path": obj.ctx_path,
-                "build_ctx": True,
             }
+            if src_exists:
+                unit_config["scratch"].update(
+                    {
+                        "ctx_path": obj.ctx_path,
+                        "build_ctx": True,
+                    }
+                )
         category_opt: List[str] | str = obj.options["progress_category"]
         if isinstance(category_opt, list):
             progress_categories.extend(category_opt)
         elif category_opt is not None:
             progress_categories.append(category_opt)
-        unit_config["metadata"].update({
-            "complete": obj.completed,
-            "reverse_fn_order": reverse_fn_order,
-            "source_path": obj.src_path,
-            "progress_categories": progress_categories,
-        })
+        unit_config["metadata"].update(
+            {
+                "complete": obj.completed,
+                "reverse_fn_order": reverse_fn_order,
+                "source_path": obj.src_path,
+                "progress_categories": progress_categories,
+            }
+        )
         objdiff_config["units"].append(unit_config)
 
     # Add DOL units