diff --git a/package/janet/janet.mk b/package/janet/janet.mk
index e076f7c461..cf4113fb17 100644
--- a/package/janet/janet.mk
+++ b/package/janet/janet.mk
@@ -11,6 +11,9 @@ JANET_LICENSE_FILES = LICENSE
 
 JANET_INSTALL_STAGING = YES
 
+# don't use posix_spawn_file_actions_addchdir[_np] (in src/core/os.c since 1.39.0)
+JANET_CFLAGS = "-DJANET_SPAWN_NO_CHDIR $(TARGET_CFLAGS)"
+
 ifeq ($(BR2_STATIC_LIBS),y)
 JANET_CONF_OPTS += -Ddynamic_modules=false
 endif