diff --git a/cde/lib/tt/bin/tt_type_comp/mp_type_comp.C b/cde/lib/tt/bin/tt_type_comp/mp_type_comp.C
index 819ce6171..21378d39b 100644
--- a/cde/lib/tt/bin/tt_type_comp/mp_type_comp.C
+++ b/cde/lib/tt/bin/tt_type_comp/mp_type_comp.C
@@ -39,6 +39,9 @@
 #include <locale.h>
 #include <stdlib.h>
 #include <string.h>
+#if defined(linux)
+#include <unistd.h>
+#endif
 #if defined(sgi)
 #include <getopt.h>
 #endif