diff --git a/configure.ac b/configure.ac
index 629881a6..1a3ccdb8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -160,7 +160,7 @@ AC_TRY_COMPILE([#include <errno.h>],
 		AC_MSG_RESULT(yes),
 		AC_MSG_RESULT(no))
 
-AC_CHECK_FUNC([pidfd_open], [enable_pidwait=yes], [
+AC_CHECK_FUNCS([pidfd_open], [enable_pidwait=yes], [
   AC_MSG_CHECKING([for __NR_pidfd_open])
   AC_COMPILE_IFELSE([AC_LANG_SOURCE([
 #include <sys/syscall.h>
diff --git a/src/pgrep.c b/src/pgrep.c
index c4ad5da3..1c15981c 100644
--- a/src/pgrep.c
+++ b/src/pgrep.c
@@ -38,9 +38,11 @@
 #include <stdbool.h>
 #include <time.h>
 
-#if defined(ENABLE_PIDWAIT) && !defined(HAVE_PIDFD_OPEN)
+#ifdef ENABLE_PIDWAIT
 #include <sys/epoll.h>
+#ifndef HAVE_PIDFD_OPEN
 #include <sys/syscall.h>
+#endif /* !HAVE_PIDFD_OPEN */
 #endif
 
 /* EXIT_SUCCESS is 0 */