diff --git a/lib/libspl/include/sys/isa_defs.h b/lib/libspl/include/sys/isa_defs.h
index 65e695adeb..677e4fda0c 100644
--- a/lib/libspl/include/sys/isa_defs.h
+++ b/lib/libspl/include/sys/isa_defs.h
@@ -50,6 +50,10 @@ extern "C" {
 #define _LP64
 #endif
 
+#if !defined(_LITTLE_ENDIAN)
+#define _LITTLE_ENDIAN
+#endif
+
 #define        _SUNOS_VTOC_16
 
 /* i386 arch specific defines */
@@ -67,6 +71,10 @@ extern "C" {
 #define _ILP32
 #endif
 
+#if !defined(_LITTLE_ENDIAN)
+#define _LITTLE_ENDIAN
+#endif
+
 #define        _SUNOS_VTOC_16
 
 /* powerpc arch specific defines */
@@ -88,6 +96,10 @@ extern "C" {
 #endif
 #endif
 
+#if !defined(_BIG_ENDIAN)
+#define _BIG_ENDIAN
+#endif
+
 #define        _SUNOS_VTOC_16
 
 #else /* Currently only x86_64, i386, and powerpc arches supported */
@@ -98,6 +110,14 @@ extern "C" {
 #error "Both _ILP32 and _LP64 are defined"
 #endif
 
+#if defined(_LITTLE_ENDIAN) && defined(_BIG_ENDIAN)
+#error "Both _LITTLE_ENDIAN and _BIG_ENDIAN are defined"
+#endif
+
+#if !defined(_LITTLE_ENDIAN) && !defined(_BIG_ENDIAN)
+#error "Neither _LITTLE_ENDIAN nor _BIG_ENDIAN are defined"
+#endif
+
 #ifdef  __cplusplus
 }
 #endif