diff --git a/user/user.h b/user/user.h
index ed10ca8..d889278 100644
--- a/user/user.h
+++ b/user/user.h
@@ -6,6 +6,9 @@ struct stat;
 
 /**
  * System calls
+ *
+ * Note that none of these calls are implemented in C. They are implemented in assembly in [usys.S](./usys.S). This file
+ * is in turn generated by the [usys.py](./usys.py) script during the build.
  */
 
 /** Create a child process */
diff --git a/user/usys.py b/user/usys.py
index 21ecd2d..896bf6d 100755
--- a/user/usys.py
+++ b/user/usys.py
@@ -42,6 +42,26 @@ assembly = "\n\n".join(map(genstub, syscalls))
 # TODO: Perhaps do some more specific assertions on the code here
 assert len(assembly) > 0, "No assembly code generated. Something is fishy"
 
+with open("kernel/syscall.h", "r") as sfile:
+    lines = list(filter(lambda x: x.startswith("#define"), sfile.readlines()))
+
+    header_calls = set([line.split()[1] for line in lines])
+    calls = set(["SYS_" + call for call in syscalls])
+
+    if header_calls == calls:
+        print("All items match in both sets.")
+    else:
+        missing_in_calls = header_calls - calls
+        missing_in_header_calls = calls - header_calls
+
+        if missing_in_calls:
+            print("These items are in header_calls but not in calls:", missing_in_calls)
+        if missing_in_header_calls:
+            print(
+                "These items are in calls but not in header_calls:",
+                missing_in_header_calls,
+            )
+
 print("# generated by usys.py - do not edit\n")
 print('#include "kernel/syscall.h"\n')
 print(assembly)