diff --git a/src/haproxy.c b/src/haproxy.c
index 89044c6..8e0e30d 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -2786,7 +2786,8 @@
 		if (global.mode & MODE_MWORKER) {
 			char pidstr[100];
 			snprintf(pidstr, sizeof(pidstr), "%d\n", getpid());
-			shut_your_big_mouth_gcc(write(pidfd, pidstr, strlen(pidstr)));
+			if (pidfd >= 0)
+				shut_your_big_mouth_gcc(write(pidfd, pidstr, strlen(pidstr)));
 		}
 
 		/* the father launches the required number of processes */