diff --git a/include/sys/zfs_context.h b/include/sys/zfs_context.h
index 0cde355be..50f43c10c 100644
--- a/include/sys/zfs_context.h
+++ b/include/sys/zfs_context.h
@@ -77,8 +77,6 @@ extern "C" {
 #include <sys/zfs_context_os.h>
 #else /* _KERNEL || _STANDALONE */
 
-#define	_SYS_SUNDDI_H
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <stddef.h>
@@ -210,12 +208,6 @@ typedef off_t loff_t;
 extern int highbit64(uint64_t i);
 extern int lowbit64(uint64_t i);
 
-/*
- * Hostname information
- */
-extern int ddi_strtoull(const char *str, char **nptr, int base,
-    u_longlong_t *result);
-
 /*
  * Kernel modules
  */
diff --git a/lib/libspl/include/sys/sunddi.h b/lib/libspl/include/sys/sunddi.h
index 8489c7139..48e0b15a4 100644
--- a/lib/libspl/include/sys/sunddi.h
+++ b/lib/libspl/include/sys/sunddi.h
@@ -21,10 +21,16 @@
  * CDDL HEADER END
  */
 /*
- * Copyright (c) 2008 by Sun Microsystems, Inc.
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
+ * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2012, Joyent, Inc. All rights reserved.
  */
 
 #ifndef	_SYS_SUNDDI_H
 #define	_SYS_SUNDDI_H
 
+extern int ddi_strtoull(const char *str, char **nptr, int base,
+    u_longlong_t *result);
+
 #endif	/* _SYS_SUNDDI_H */