diff --git a/src/bootctl/bootctl-install.c b/src/bootctl/bootctl-install.c
index 8399a2da72..50ab7b602c 100644
--- a/src/bootctl/bootctl-install.c
+++ b/src/bootctl/bootctl-install.c
@@ -2035,6 +2035,10 @@ int vl_method_install(
                 if (p.context.root_fd < 0)
                         return log_debug_errno(p.context.root_fd, "Failed to acquire root fd from Varlink: %m");
 
+                r = fd_verify_safe_flags_full(p.context.root_fd, O_DIRECTORY);
+                if (r < 0)
+                        return sd_varlink_error_invalid_parameter_name(link, "rootFileDescriptor");
+
                 r = fd_verify_directory(p.context.root_fd);
                 if (r < 0)
                         return log_debug_errno(r, "Specified file descriptor does not refer to a directory: %m");
@@ -2047,15 +2051,11 @@ int vl_method_install(
                         if (empty_or_root(p.context.root))
                                 p.context.root = mfree(p.context.root);
                 }
-        }
-
-        if (p.context.root_fd < 0 && p.context.root) {
+        } else if (p.context.root) {
                 p.context.root_fd = open(p.context.root, O_RDONLY|O_CLOEXEC|O_DIRECTORY);
                 if (p.context.root_fd < 0)
                         return log_debug_errno(errno, "Failed to open '%s': %m", p.context.root);
-        }
-
-        if (p.context.root_fd < 0)
+        } else
                 p.context.root_fd = XAT_FDROOT;
 
         if (p.context.entry_token_type < 0)
diff --git a/src/shared/varlink-io.systemd.BootControl.c b/src/shared/varlink-io.systemd.BootControl.c
index a24b4b076e..c369b134ef 100644
--- a/src/shared/varlink-io.systemd.BootControl.c
+++ b/src/shared/varlink-io.systemd.BootControl.c
@@ -128,7 +128,7 @@ static SD_VARLINK_DEFINE_METHOD(
                 SD_VARLINK_FIELD_COMMENT("Index into array of file descriptors passed along with this message, pointing to file descriptor to root file system to operate on"),
                 SD_VARLINK_DEFINE_INPUT(rootFileDescriptor, SD_VARLINK_INT, SD_VARLINK_NULLABLE),
                 SD_VARLINK_FIELD_COMMENT("Root directory to operate relative to. If both this and rootFileDescriptor is specified, this is purely informational. If only this is specified, it is what will be used."),
-                SD_VARLINK_DEFINE_INPUT(rootDirectory, SD_VARLINK_INT, SD_VARLINK_NULLABLE),
+                SD_VARLINK_DEFINE_INPUT(rootDirectory, SD_VARLINK_STRING, SD_VARLINK_NULLABLE),
                 SD_VARLINK_FIELD_COMMENT("Selects how to identify boot entries"),
                 SD_VARLINK_DEFINE_INPUT_BY_TYPE(bootEntryTokenType, BootEntryTokenType, SD_VARLINK_NULLABLE),
                 SD_VARLINK_FIELD_COMMENT("If true the boot loader will be registered in an EFI boot entry via EFI variables, otherwise this is omitted"),