diff --git a/src/haproxy.c b/src/haproxy.c
index f55a97b..2163326 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -3680,8 +3680,11 @@
 
 #ifdef USE_CPU_AFFINITY
 		/* Now the CPU affinity for all threads */
-		if (global.cpu_map.proc_t1[relative_pid-1])
-			global.cpu_map.thread[0] &= global.cpu_map.proc_t1[relative_pid-1];
+
+		/* If on multiprocess, use proc_t1 except for the first process.
+		 */
+		if ((relative_pid - 1) > 0)
+			global.cpu_map.thread[0] = global.cpu_map.proc_t1[relative_pid-1];
 
 		for (i = 0; i < global.nbthread; i++) {
 			if (global.cpu_map.proc[relative_pid-1])