diff --git a/gum/backend-windows/gumprocess-windows.c b/gum/backend-windows/gumprocess-windows.c
index 9ff3745fa..e564f5cf4 100644
--- a/gum/backend-windows/gumprocess-windows.c
+++ b/gum/backend-windows/gumprocess-windows.c
@@ -1312,7 +1312,10 @@ gum_windows_cpu_type_from_pid (guint pid,
 
     switch (code)
     {
-      /* TODO: Handle code for when PID doesn't exist. */
+      case ERROR_INVALID_PARAMETER:
+        g_set_error (error, GUM_ERROR, GUM_ERROR_NOT_FOUND,
+            "Process not found");
+        break;
       case ERROR_ACCESS_DENIED:
         g_set_error (error, GUM_ERROR, GUM_ERROR_PERMISSION_DENIED,
             "Permission denied");