diff --git a/libc/kernel/uapi/linux/magic.h b/libc/kernel/uapi/linux/magic.h
index 82b9dce..479ae81 100644
--- a/libc/kernel/uapi/linux/magic.h
+++ b/libc/kernel/uapi/linux/magic.h
@@ -97,6 +97,7 @@
 #define BALLOON_KVM_MAGIC 0x13661366
 #define ZSMALLOC_MAGIC 0x58295829
 #define DMA_BUF_MAGIC 0x444d4142
+#define DEVMEM_MAGIC 0x454d444d
 #define Z3FOLD_MAGIC 0x33
 #define PPC_CMM_MAGIC 0xc7571590
 #endif