diff --git a/Utilities/cmlibarchive/build/cmake/config.h.in b/Utilities/cmlibarchive/build/cmake/config.h.in
index b1690515d7..b404be37ed 100644
--- a/Utilities/cmlibarchive/build/cmake/config.h.in
+++ b/Utilities/cmlibarchive/build/cmake/config.h.in
@@ -1,4 +1,7 @@
 /* config.h.  Generated from build/cmake/config.h.in by cmake configure */
+#if defined(__osf__)
+# define _OSF_SOURCE
+#endif
 
 /*
  * Ensure we have C99-style int64_t, etc, all defined.
diff --git a/Utilities/cmlibarchive/libarchive/archive.h b/Utilities/cmlibarchive/libarchive/archive.h
index 14c2aed989..75475ca4c9 100644
--- a/Utilities/cmlibarchive/libarchive/archive.h
+++ b/Utilities/cmlibarchive/libarchive/archive.h
@@ -41,7 +41,7 @@
  */
 #if defined(__BORLANDC__) && __BORLANDC__ >= 0x560
 # include <stdint.h>
-#elif !defined(__WATCOMC__) && !defined(_MSC_VER) && !defined(__INTERIX) && !defined(__BORLANDC__) && !defined(_SCO_DS)
+#elif !defined(__WATCOMC__) && !defined(_MSC_VER) && !defined(__INTERIX) && !defined(__BORLANDC__) && !defined(_SCO_DS) && !defined(__osf__)
 # include <inttypes.h>
 #endif
 
@@ -65,7 +65,7 @@
 # endif
 #else
 # include <unistd.h>  /* ssize_t, uid_t, and gid_t */
-# if defined(_SCO_DS)
+# if defined(_SCO_DS) || defined(__osf__)
 #  define	__LA_INT64_T	long long
 # else
 #  define	__LA_INT64_T	int64_t
diff --git a/Utilities/cmlibarchive/libarchive/archive_endian.h b/Utilities/cmlibarchive/libarchive/archive_endian.h
index edc90ee6a8..1dd8536c48 100644
--- a/Utilities/cmlibarchive/libarchive/archive_endian.h
+++ b/Utilities/cmlibarchive/libarchive/archive_endian.h
@@ -47,7 +47,7 @@
  */
 #if defined(__WATCOMC__) || defined(__sgi) || defined(__hpux) || defined(__BORLANDC__)
 #define	inline
-#elif defined(_MSC_VER)
+#elif defined(_MSC_VER) || defined(__osf__)
 #define inline __inline
 #endif
 
diff --git a/Utilities/cmlibarchive/libarchive/archive_entry.h b/Utilities/cmlibarchive/libarchive/archive_entry.h
index fcd76573c1..906779a822 100644
--- a/Utilities/cmlibarchive/libarchive/archive_entry.h
+++ b/Utilities/cmlibarchive/libarchive/archive_entry.h
@@ -64,7 +64,7 @@
 # endif
 #else
 #include <unistd.h>
-# if defined(_SCO_DS)
+# if defined(_SCO_DS) || defined(__osf__)
 #  define	__LA_INT64_T	long long
 # else
 #  define	__LA_INT64_T	int64_t