diff --git a/mdadm.h b/mdadm.h
index a761f29..7ffac8f 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -25,9 +25,9 @@
 #define	_GNU_SOURCE
 #define _FILE_OFFSET_BITS 64
 #include	<unistd.h>
-#if !defined(__dietlibc__) && !defined(__KLIBC__)
+#ifdef __GLIBC__
 extern __off64_t lseek64 __P ((int __fd, __off64_t __offset, int __whence));
-#else
+#elif !defined(lseek64)
 # if defined(__NO_STAT64) || __WORDSIZE != 32
 # define lseek64 lseek
 # endif