diff -urN a/extras/ext4_utils/sha1.c b/extras/ext4_utils/sha1.c
--- a/extras/ext4_utils/sha1.c	2015-09-15 06:06:00.000000000 +0000
+++ b/extras/ext4_utils/sha1.c	2016-04-20 23:38:47.459902412 +0000
@@ -17,9 +17,6 @@
 
 #define SHA1HANDSOFF		/* Copies data before messing with it. */
 
-#ifndef USE_MINGW
-#include <sys/cdefs.h>
-#endif
 #include <sys/types.h>
 #include <assert.h>
 #include <string.h>
diff -urN a/extras/ext4_utils/sha1.h b/extras/ext4_utils/sha1.h
--- a/extras/ext4_utils/sha1.h	2015-09-15 06:06:00.000000000 +0000
+++ b/extras/ext4_utils/sha1.h	2016-04-21 08:05:20.406038068 +0000
@@ -17,11 +17,6 @@
 typedef unsigned int uint32_t;
 typedef unsigned int u_int32_t;
 typedef unsigned int u_int;
-
-#define __BEGIN_DECLS
-#define __END_DECLS
-#else
-#include <sys/cdefs.h>
 #endif
 
 #define SHA1_DIGEST_LENGTH		20
@@ -33,11 +28,15 @@
 	u_char buffer[64];
 } SHA1_CTX;
 
-__BEGIN_DECLS
+#ifdef __cplusplus
+extern "C" {
+#endif
 void	SHA1Transform(uint32_t[5], const u_char[64]);
 void	SHA1Init(SHA1_CTX *);
 void	SHA1Update(SHA1_CTX *, const u_char *, u_int);
 void	SHA1Final(u_char[SHA1_DIGEST_LENGTH], SHA1_CTX *);
-__END_DECLS
+#ifdef __cplusplus
+}
+#endif
 
 #endif /* _SYS_SHA1_H_ */