diff --git a/libiptc/libip4tc.c b/libiptc/libip4tc.c
index 267382e..df7fee2 100644
--- a/libiptc/libip4tc.c
+++ b/libiptc/libip4tc.c
@@ -16,6 +16,7 @@
 #include <errno.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <unistd.h>
 
 #ifdef DEBUG_CONNTRACK
 #define inline
diff --git a/libiptc/libip6tc.c b/libiptc/libip6tc.c
index 31fbe07..b09d439 100644
--- a/libiptc/libip6tc.c
+++ b/libiptc/libip6tc.c
@@ -16,6 +16,7 @@
 #include <errno.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <unistd.h>
 #include <arpa/inet.h>
 
 #ifdef DEBUG_CONNTRACK