diff --git a/Grow.c b/Grow.c
index b7234e4..90b84d7 100644
--- a/Grow.c
+++ b/Grow.c
@@ -2265,6 +2265,7 @@ started:
 	default:
 		return 0;
 	case 0:
+		map_fork();
 		break;
 	}
 
@@ -2421,6 +2422,7 @@ int reshape_container(char *container, char *devname,
 		printf(Name ": multi-array reshape continues in background\n");
 		return 0;
 	case 0: /* child */
+		map_fork();
 		break;
 	}
 
diff --git a/Incremental.c b/Incremental.c
index 791ad85..a3e05a7 100644
--- a/Incremental.c
+++ b/Incremental.c
@@ -1469,6 +1469,7 @@ static int Incremental_container(struct supertype *st, char *devname,
 					"Cannot activate array(s).\n");
 		/* free container data and exit */
 		sysfs_free(list);
+		map_unlock(&map);
 		return 2;
 	}
 
@@ -1532,6 +1533,7 @@ static int Incremental_container(struct supertype *st, char *devname,
 					fprintf(stderr, Name ": array %s/%s is "
 						"explicitly ignored by mdadm.conf\n",
 						match->container, match->member);
+				map_unlock(&map);
 				return 2;
 			}
 			if (match)
@@ -1547,6 +1549,7 @@ static int Incremental_container(struct supertype *st, char *devname,
 		if (mdfd < 0) {
 			fprintf(stderr, Name ": failed to open %s: %s.\n",
 				chosen_name, strerror(errno));
+			map_unlock(&map);
 			return 2;
 		}
 
diff --git a/mapfile.c b/mapfile.c
index ff1e973..997f095 100644
--- a/mapfile.c
+++ b/mapfile.c
@@ -159,6 +159,18 @@ void map_unlock(struct map_ent **melp)
 	lf = NULL;
 }
 
+void map_fork(void)
+{
+	/* We are forking, so must close the lock file.
+	 * Don't risk flushing anything though.
+	 */
+	if (lf) {
+		close(fileno(lf));
+		fclose(lf);
+		lf = NULL;
+	}
+}
+
 void map_add(struct map_ent **melp,
 	    int devnum, char *metadata, int uuid[4], char *path)
 {
diff --git a/mdadm.h b/mdadm.h
index 8dd37d9..9165f7a 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -427,6 +427,7 @@ extern void map_add(struct map_ent **melp,
 		    int devnum, char *metadata, int uuid[4], char *path);
 extern int map_lock(struct map_ent **melp);
 extern void map_unlock(struct map_ent **melp);
+extern void map_fork(void);
 
 /* various details can be requested */
 enum sysfs_read_flags {