diff --git a/lib/libbe/be.c b/lib/libbe/be.c
--- a/lib/libbe/be.c
+++ b/lib/libbe/be.c
@@ -961,6 +961,17 @@
 	if (!zfs_name_valid(name, ZFS_TYPE_DATASET))
 		return (BE_ERR_INVALIDNAME);
 
+	/*
+	 * ZFS allows spaces in boot environment names, but the kernel can't
+	 * handle booting from such a dataset right now.  vfs.root.mountfrom
+	 * is defined to be a space-separated list, and there's no protocol for
+	 * escaping whitespace in the path component of a dev:path spec.  So
+	 * while loader can handle this situation alright, it can't safely pass
+	 * it on to mountroot.
+	 */
+	if (strchr(name, ' ') != NULL)
+		return (BE_ERR_INVALIDNAME);
+
 	return (BE_ERR_SUCCESS);
 }
 
diff --git a/sbin/bectl/bectl.c b/sbin/bectl/bectl.c
--- a/sbin/bectl/bectl.c
+++ b/sbin/bectl/bectl.c
@@ -134,7 +134,6 @@
 	return (NULL);
 }
 
-
 static int
 bectl_cmd_activate(int argc, char *argv[])
 {
@@ -233,10 +232,7 @@
 	bootenv = *argv;
 
 	err = BE_ERR_SUCCESS;
-	if (strchr(bootenv, ' ') != NULL)
-		/* BE datasets with spaces are not bootable */
-		err = BE_ERR_INVALIDNAME;
-	else if ((atpos = strchr(bootenv, '@')) != NULL) {
+	if ((atpos = strchr(bootenv, '@')) != NULL) {
 		/*
 		 * This is the "create a snapshot variant". No new boot
 		 * environment is to be created here.
@@ -478,7 +474,6 @@
 	dest = argv[2];
 
 	err = be_rename(be, src, dest);
-
 	switch (err) {
 	case BE_ERR_SUCCESS:
 		break;
@@ -487,7 +482,7 @@
 		    src, dest);
 	}
 
-	return (0);
+	return (err);
 }
 
 static int