diff --git a/ebpf/aya-ebpf/src/lib.rs b/ebpf/aya-ebpf/src/lib.rs
index d842abaf..9da648a2 100644
--- a/ebpf/aya-ebpf/src/lib.rs
+++ b/ebpf/aya-ebpf/src/lib.rs
@@ -113,6 +113,16 @@ mod intrinsics {
 #[cfg(target_arch = "bpf")]
 pub use intrinsics::*;
 
+// A reimplementation of the BPF_F_ADJ_ROOM_ENCAP_L2(len) macro of the kernel, to use to construct
+// flags to pass to bpf_skb_adjust_room.
+// https://elixir.bootlin.com/linux/v6.16.4/source/include/uapi/linux/bpf.h#L6149
+#[inline(always)]
+#[allow(non_snake_case)]
+pub fn BPF_F_ADJ_ROOM_ENCAP_L2(len: u64) -> u64 {
+    (len & bindings::BPF_ADJ_ROOM_ENCAP_L2_MASK as u64)
+        << bindings::BPF_ADJ_ROOM_ENCAP_L2_SHIFT as u64
+}
+
 /// Check if a value is within a range, using conditional forms compatible with
 /// the verifier.
 #[inline(always)]