diff --git a/app/overlay-memfault.conf b/app/overlay-memfault.conf
index 2658c361..c3239076 100644
--- a/app/overlay-memfault.conf
+++ b/app/overlay-memfault.conf
@@ -13,3 +13,6 @@ CONFIG_MEMFAULT_HEAP_STATS=y
 CONFIG_MEMFAULT_NCS_LOCATION_METRICS=y
 CONFIG_MEMFAULT_HTTP_DEDICATED_WORKQUEUE_STACK_SIZE=1560
 CONFIG_MEMFAULT_COREDUMP_FULL_THREAD_STACKS=y
+
+# Memfault depends on POSIX, disable unneeded POSIX features
+CONFIG_POSIX_FILE_SYSTEM=n