diff --git a/cde/lib/tt/bin/tttar/tttar.C b/cde/lib/tt/bin/tttar/tttar.C
index 69c78e680..c26432ff4 100644
--- a/cde/lib/tt/bin/tttar/tttar.C
+++ b/cde/lib/tt/bin/tttar/tttar.C
@@ -37,7 +37,7 @@
 #include <stdlib.h>
 #include <sys/param.h>
 #include <sys/stat.h>
-#if defined(__osf__)
+#if defined(__osf__) || defined(linux)
 #include <unistd.h>
 #else
 #if !defined(USL) && !defined(__uxp__)
diff --git a/cde/lib/tt/bin/tttar/tttar_api.C b/cde/lib/tt/bin/tttar/tttar_api.C
index 6b0f68b57..7622dcbb8 100644
--- a/cde/lib/tt/bin/tttar/tttar_api.C
+++ b/cde/lib/tt/bin/tttar/tttar_api.C
@@ -33,7 +33,7 @@
  */
 
 #include <errno.h>
-#if defined(__osf__)
+#if defined(__osf__) || defined(linux)
 #include <unistd.h>
 #else
 #ifndef USL
diff --git a/cde/lib/tt/bin/tttar/tttar_spec.C b/cde/lib/tt/bin/tttar/tttar_spec.C
index 72a5850ec..4c4df4ab8 100644
--- a/cde/lib/tt/bin/tttar/tttar_spec.C
+++ b/cde/lib/tt/bin/tttar/tttar_spec.C
@@ -32,7 +32,7 @@
  *
  */
 
-#if defined(__osf__)
+#if defined(__osf__) || defined(linux)
 #include <unistd.h>
 #else
 #if defined (USL) || defined(__uxp__)