diff --git a/src/libply/ply-utils.h b/src/libply/ply-utils.h
index 5ca327d1..abe332a4 100644
--- a/src/libply/ply-utils.h
+++ b/src/libply/ply-utils.h
@@ -25,6 +25,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <unistd.h>
+#include <sys/types.h>
 
 #ifndef MIN
 #define MIN(a,b) ((a) <= (b)? (a) : (b))