diff --git a/include/sys/select.h b/include/sys/select.h
index 7b136d44927..912d5d1ca3a 100644
--- a/include/sys/select.h
+++ b/include/sys/select.h
@@ -86,11 +86,11 @@
 /* Standard helper macros */
 
 #define FD_CLR(fd,set) \
-  ((((fd_set*)(set))->arr)[_FD_NDX(fd)] &= ~(1 << _FD_BIT(fd)))
+  ((((fd_set*)(set))->arr)[_FD_NDX(fd)] &= ~(1ul << _FD_BIT(fd)))
 #define FD_SET(fd,set) \
-  ((((fd_set*)(set))->arr)[_FD_NDX(fd)] |= (1 << _FD_BIT(fd)))
+  ((((fd_set*)(set))->arr)[_FD_NDX(fd)] |= (1ul << _FD_BIT(fd)))
 #define FD_ISSET(fd,set) \
-  (((((fd_set*)(set))->arr)[_FD_NDX(fd)] & (1 << _FD_BIT(fd))) != 0)
+  (((((fd_set*)(set))->arr)[_FD_NDX(fd)] & (1ul << _FD_BIT(fd))) != 0)
 #define FD_ZERO(set) \
    memset((set), 0, sizeof(fd_set))