diff --git a/platformio.ini b/platformio.ini
index db933030eb..ed0d3b9a3c 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -89,6 +89,11 @@ build_flags = ${arduino_base.build_flags}
   -D NRF52_PLATFORM
   -D LFS_NO_ASSERT=1
   -D EXTRAFS=1
+  ; Enlarge the Arduino loop_task stack (framework default 4KB / 1024 words is too
+  ; small for LittleFS file opens from loop(), which overflow it and corrupt adjacent
+  ; heap). 2048 words = 8KB. Requires the framework's LOOP_STACK_SZ #define to be
+  ; #ifndef-guarded (Adafruit_nRF52_Arduino) so this override is honoured.
+  -D LOOP_STACK_SZ=2048
 lib_deps =
   ${arduino_base.lib_deps}
   https://github.com/oltaco/CustomLFS#0.2.2