diff --git a/src/basic/missing_syscall_def.h b/src/basic/missing_syscall_def.h
index d078bf70df3..88df92db611 100644
--- a/src/basic/missing_syscall_def.h
+++ b/src/basic/missing_syscall_def.h
@@ -4,6 +4,7 @@
  * Use 'ninja -C build update-syscall-tables' to download new syscall tables,
  * and 'ninja -C build update-syscall-header' to regenerate this file.
  */
+#pragma once
 
 /* Note: if this code looks strange, this is because it is derived from the same
  * template as the per-syscall blocks below. */
diff --git a/src/basic/missing_syscalls.py b/src/basic/missing_syscalls.py
index 2694e83b988..83199bb1d75 100644
--- a/src/basic/missing_syscalls.py
+++ b/src/basic/missing_syscalls.py
@@ -142,6 +142,7 @@ def print_syscall_defs(syscalls, tables, out):
  * Use 'ninja -C build update-syscall-tables' to download new syscall tables,
  * and 'ninja -C build update-syscall-header' to regenerate this file.
  */
+#pragma once
 ''',
           file=out)
     print(ARCH_CHECK, file=out)
diff --git a/src/boot/efi/xbootldr.h b/src/boot/efi/xbootldr.h
index 4cb370af29c..205ce71edf0 100644
--- a/src/boot/efi/xbootldr.h
+++ b/src/boot/efi/xbootldr.h
@@ -1,4 +1,5 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
 
 #include <efi.h>
 
diff --git a/src/network/networkd-wiphy.h b/src/network/networkd-wiphy.h
index 072a7e5fdd5..b40354704be 100644
--- a/src/network/networkd-wiphy.h
+++ b/src/network/networkd-wiphy.h
@@ -1,4 +1,5 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
 
 #include <inttypes.h>