diff --git a/sys/sys/elf32.h b/sys/sys/elf32.h
index 03a546c892c3..0aa3142ed119 100644
--- a/sys/sys/elf32.h
+++ b/sys/sys/elf32.h
@@ -254,4 +254,10 @@ typedef struct {
 	Elf32_Half	si_flags;	/* per symbol flags */
 } Elf32_Syminfo;
 
+typedef struct {
+	Elf32_Word	ch_type;
+	Elf32_Word	ch_size;
+	Elf32_Word	ch_addralign;
+} Elf32_Chdr;
+
 #endif /* !_SYS_ELF32_H_ */
diff --git a/sys/sys/elf64.h b/sys/sys/elf64.h
index f0696196d55f..a309dfc6843e 100644
--- a/sys/sys/elf64.h
+++ b/sys/sys/elf64.h
@@ -257,4 +257,11 @@ typedef struct {
 	Elf64_Half	si_flags;	/* per symbol flags */
 } Elf64_Syminfo;
 
+typedef struct {
+	Elf64_Word	ch_type;
+	Elf64_Word	ch_reserved;
+	Elf64_Xword	ch_size;
+	Elf64_Xword	ch_addralign;
+} Elf64_Chdr;
+
 #endif /* !_SYS_ELF64_H_ */
diff --git a/sys/sys/elf_common.h b/sys/sys/elf_common.h
index ede4b13a2c5e..e8a8709f37ef 100644
--- a/sys/sys/elf_common.h
+++ b/sys/sys/elf_common.h
@@ -849,6 +849,13 @@ typedef struct {
 #define	SYMINFO_CURRENT		1
 #define	SYMINFO_NUM		2
 
+/* Values for ch_type (compressed section headers). */
+#define	ELFCOMPRESS_ZLIB	1	/* ZLIB/DEFLATE */
+#define	ELFCOMPRESS_LOOS	0x60000000	/* OS-specific */
+#define	ELFCOMPRESS_HIOS	0x6fffffff
+#define	ELFCOMPRESS_LOPROC	0x70000000	/* Processor-specific */
+#define	ELFCOMPRESS_HIPROC	0x7fffffff
+
 /*
  * Relocation types.
  *