diff --git a/tools/widl/client.c b/tools/widl/client.c
index 1dbbbc693a2..3197b732e04 100644
--- a/tools/widl/client.c
+++ b/tools/widl/client.c
@@ -252,6 +252,8 @@ static void write_function_stubs(type_t *iface)
         }
         if (!is_void(def->type, NULL))
             proc_offset += get_size_procformatstring_var(def);
+        else
+            proc_offset += 2; /* FC_END and FC_PAD */
 
         indent--;
         print_client("}\n");
diff --git a/tools/widl/server.c b/tools/widl/server.c
index d1ea5f080a6..8cc33daab67 100644
--- a/tools/widl/server.c
+++ b/tools/widl/server.c
@@ -343,6 +343,8 @@ static void write_function_stubs(type_t *iface)
         }
         if (!is_void(def->type, NULL))
             proc_offset += get_size_procformatstring_var(def);
+        else
+            proc_offset += 2; /* FC_END and FC_PAD */
 
         func = PREV_LINK(func);
     }