1 files changed, 2 insertions, 0 deletions
diff --git a/src/tryulong64.c b/src/tryulong64.c
index 003548a..a4b9839 100644
--- a/src/tryulong64.c
+++ b/src/tryulong64.c
@@ -1,5 +1,7 @@
 /* Public domain. */
 
+#include <unistd.h>
+
 int main()
 {
   unsigned long u;