diff --git a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/TARGET_EFM32HG_STK3400/device.h b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/TARGET_EFM32HG_STK3400/device.h
index 0ef7e6deb3..d1873076f9 100644
--- a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/TARGET_EFM32HG_STK3400/device.h
+++ b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/TARGET_EFM32HG_STK3400/device.h
@@ -50,6 +50,11 @@
 
 #define DEVICE_LOWPOWERTIMER    1
 
+// Redefine OPEN_MAX from sys_limits.h to save on RAM.
+// Effect: maximum amount of file handlers = OPEN_MAX
+// This is not going to have an impact, since this is a RAM-limited part anyway.
+#define OPEN_MAX                24
+
 #include "objects.h"
 #include "Modules.h"
 #include "device_peripherals.h"
diff --git a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/TARGET_EFM32ZG_STK3200/device.h b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/TARGET_EFM32ZG_STK3200/device.h
index 0ef7e6deb3..d7b54e2aaf 100644
--- a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/TARGET_EFM32ZG_STK3200/device.h
+++ b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/TARGET_EFM32ZG_STK3200/device.h
@@ -50,6 +50,11 @@
 
 #define DEVICE_LOWPOWERTIMER    1
 
+// Redefine OPEN_MAX from sys_limits.h to save on RAM.
+// Effect: maximum amount of file handlers = OPEN_MAX
+// This is not going to have an impact, since this is a RAM-limited part anyway.
+#define OPEN_MAX                8
+
 #include "objects.h"
 #include "Modules.h"
 #include "device_peripherals.h"