diff --git a/stmhal/boards/ESPRUINO_PICO/mpconfigboard.h b/stmhal/boards/ESPRUINO_PICO/mpconfigboard.h
index e84822957d..d065180d8a 100644
--- a/stmhal/boards/ESPRUINO_PICO/mpconfigboard.h
+++ b/stmhal/boards/ESPRUINO_PICO/mpconfigboard.h
@@ -1,6 +1,9 @@
 #define MICROPY_HW_BOARD_NAME       "Espruino Pico"
 #define MICROPY_HW_MCU_NAME         "STM32F401CD"
 
+#define MICROPY_EMIT_THUMB          (0)
+#define MICROPY_EMIT_INLINE_THUMB   (0)
+#define MICROPY_PY_BUILTINS_COMPLEX (0)
 #define MICROPY_PY_USOCKET          (0)
 #define MICROPY_PY_NETWORK          (0)
 
diff --git a/stmhal/boards/ESPRUINO_PICO/mpconfigboard.mk b/stmhal/boards/ESPRUINO_PICO/mpconfigboard.mk
index 4c44022c32..d531a594a1 100644
--- a/stmhal/boards/ESPRUINO_PICO/mpconfigboard.mk
+++ b/stmhal/boards/ESPRUINO_PICO/mpconfigboard.mk
@@ -2,3 +2,6 @@ MCU_SERIES = f4
 CMSIS_MCU = STM32F401xE
 AF_FILE = boards/stm32f401_af.csv
 LD_FILE = boards/stm32f401xd.ld
+
+# Don't include default frozen modules because MCU is tight on flash space
+FROZEN_MPY_DIR ?=
diff --git a/stmhal/mpconfigport.h b/stmhal/mpconfigport.h
index 96a330d139..d3ce11e02d 100644
--- a/stmhal/mpconfigport.h
+++ b/stmhal/mpconfigport.h
@@ -39,8 +39,12 @@
 
 // emitters
 #define MICROPY_PERSISTENT_CODE_LOAD (1)
+#ifndef MICROPY_EMIT_THUMB
 #define MICROPY_EMIT_THUMB          (1)
+#endif
+#ifndef MICROPY_EMIT_INLINE_THUMB
 #define MICROPY_EMIT_INLINE_THUMB   (1)
+#endif
 
 // compiler configuration
 #define MICROPY_COMP_MODULE_CONST   (1)