diff --git a/py/objfun.c b/py/objfun.c
index b8ebce7a39..ba3ce6279f 100644
--- a/py/objfun.c
+++ b/py/objfun.c
@@ -98,42 +98,13 @@ const mp_obj_type_t fun_native_type = {
     .call_n_kw = fun_native_call_n_kw,
 };
 
-mp_obj_t rt_make_function_0(mp_fun_0_t fun) {
+// fun must have the correct signature for n_args fixed arguments
+mp_obj_t rt_make_function_n(int n_args, void *fun) {
     mp_obj_fun_native_t *o = m_new_obj(mp_obj_fun_native_t);
     o->base.type = &fun_native_type;
     o->is_kw = false;
-    o->n_args_min = 0;
-    o->n_args_max = 0;
-    o->fun = fun;
-    return o;
-}
-
-mp_obj_t rt_make_function_1(mp_fun_1_t fun) {
-    mp_obj_fun_native_t *o = m_new_obj(mp_obj_fun_native_t);
-    o->base.type = &fun_native_type;
-    o->is_kw = false;
-    o->n_args_min = 1;
-    o->n_args_max = 1;
-    o->fun = fun;
-    return o;
-}
-
-mp_obj_t rt_make_function_2(mp_fun_2_t fun) {
-    mp_obj_fun_native_t *o = m_new_obj(mp_obj_fun_native_t);
-    o->base.type = &fun_native_type;
-    o->is_kw = false;
-    o->n_args_min = 2;
-    o->n_args_max = 2;
-    o->fun = fun;
-    return o;
-}
-
-mp_obj_t rt_make_function_3(mp_fun_3_t fun) {
-    mp_obj_fun_native_t *o = m_new_obj(mp_obj_fun_native_t);
-    o->base.type = &fun_native_type;
-    o->is_kw = false;
-    o->n_args_min = 3;
-    o->n_args_max = 3;
+    o->n_args_min = n_args;
+    o->n_args_max = n_args;
     o->fun = fun;
     return o;
 }
diff --git a/py/objstr.c b/py/objstr.c
index a1c35bad3b..f48bde6001 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -3,7 +3,6 @@
 #include <stdarg.h>
 #include <string.h>
 #include <assert.h>
-#include <sys/types.h>
 
 #include "nlr.h"
 #include "misc.h"
diff --git a/py/runtime.c b/py/runtime.c
index 766a321bc4..f43e804b40 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -587,12 +587,7 @@ mp_obj_t rt_make_function_from_id(int unique_code_id) {
             fun = mp_obj_new_fun_bc(c->n_args, c->n_locals + c->n_stack, c->u_byte.code);
             break;
         case MP_CODE_NATIVE:
-            switch (c->n_args) {
-                case 0: fun = rt_make_function_0(c->u_native.fun); break;
-                case 1: fun = rt_make_function_1((mp_fun_1_t)c->u_native.fun); break;
-                case 2: fun = rt_make_function_2((mp_fun_2_t)c->u_native.fun); break;
-                default: assert(0); fun = mp_const_none;
-            }
+            fun = rt_make_function_n(c->n_args, c->u_native.fun);
             break;
         case MP_CODE_INLINE_ASM:
             fun = mp_obj_new_fun_asm(c->n_args, c->u_inline_asm.fun);
diff --git a/py/runtime.h b/py/runtime.h
index ac53e14110..32cb47684f 100644
--- a/py/runtime.h
+++ b/py/runtime.h
@@ -12,10 +12,8 @@ void rt_store_global(qstr qstr, mp_obj_t obj);
 mp_obj_t rt_unary_op(int op, mp_obj_t arg);
 mp_obj_t rt_binary_op(int op, mp_obj_t lhs, mp_obj_t rhs);
 mp_obj_t rt_make_function_from_id(int unique_code_id);
-mp_obj_t rt_make_function_0(mp_fun_0_t f);
-mp_obj_t rt_make_function_1(mp_fun_1_t f);
-mp_obj_t rt_make_function_2(mp_fun_2_t f);
-mp_obj_t rt_make_function_var(int n_args_min, mp_fun_var_t f);
+mp_obj_t rt_make_function_n(int n_args, void *fun); // fun must have the correct signature for n_args fixed arguments
+mp_obj_t rt_make_function_var(int n_args_min, mp_fun_var_t fun);
 mp_obj_t rt_make_function_var_between(int n_args_min, int n_args_max, mp_fun_var_t fun); // min and max are inclusive
 mp_obj_t rt_make_closure_from_id(int unique_code_id, mp_obj_t closure_tuple);
 mp_obj_t rt_call_function_0(mp_obj_t fun);
diff --git a/stm/audio.c b/stm/audio.c
index 34adefbcd6..e2aa32b9fc 100644
--- a/stm/audio.c
+++ b/stm/audio.c
@@ -91,8 +91,8 @@ void audio_init(void) {
 
     // Python interface
     mp_obj_t m = mp_obj_new_module(qstr_from_str_static("audio"));
-    rt_store_attr(m, qstr_from_str_static("dac"), rt_make_function_1(pyb_audio_dac));
-    rt_store_attr(m, qstr_from_str_static("is_full"), rt_make_function_0(pyb_audio_is_full));
-    rt_store_attr(m, qstr_from_str_static("fill"), rt_make_function_1(pyb_audio_fill));
+    rt_store_attr(m, qstr_from_str_static("dac"), rt_make_function_n(1, pyb_audio_dac));
+    rt_store_attr(m, qstr_from_str_static("is_full"), rt_make_function_n(0, pyb_audio_is_full));
+    rt_store_attr(m, qstr_from_str_static("fill"), rt_make_function_n(1, pyb_audio_fill));
     rt_store_name(qstr_from_str_static("audio"), m);
 }
diff --git a/stm/lcd.c b/stm/lcd.c
index 70d1a26423..82e42b779d 100644
--- a/stm/lcd.c
+++ b/stm/lcd.c
@@ -220,13 +220,13 @@ void lcd_init(void) {
 
     // Python interface
     mp_obj_t m = mp_obj_new_module(qstr_from_str_static("lcd"));
-    rt_store_attr(m, qstr_from_str_static("lcd8"), rt_make_function_2(lcd_draw_pixel_8));
-    rt_store_attr(m, qstr_from_str_static("clear"), rt_make_function_0(lcd_pix_clear));
-    rt_store_attr(m, qstr_from_str_static("get"), rt_make_function_2(lcd_pix_get));
-    rt_store_attr(m, qstr_from_str_static("set"), rt_make_function_2(lcd_pix_set));
-    rt_store_attr(m, qstr_from_str_static("reset"), rt_make_function_2(lcd_pix_reset));
-    rt_store_attr(m, qstr_from_str_static("show"), rt_make_function_0(lcd_pix_show));
-    rt_store_attr(m, qstr_from_str_static("text"), rt_make_function_1(lcd_print));
+    rt_store_attr(m, qstr_from_str_static("lcd8"), rt_make_function_n(2, lcd_draw_pixel_8));
+    rt_store_attr(m, qstr_from_str_static("clear"), rt_make_function_n(0, lcd_pix_clear));
+    rt_store_attr(m, qstr_from_str_static("get"), rt_make_function_n(2, lcd_pix_get));
+    rt_store_attr(m, qstr_from_str_static("set"), rt_make_function_n(2, lcd_pix_set));
+    rt_store_attr(m, qstr_from_str_static("reset"), rt_make_function_n(2, lcd_pix_reset));
+    rt_store_attr(m, qstr_from_str_static("show"), rt_make_function_n(0, lcd_pix_show));
+    rt_store_attr(m, qstr_from_str_static("text"), rt_make_function_n(1, lcd_print));
     rt_store_name(qstr_from_str_static("lcd"), m);
 }
 
diff --git a/stm/main.c b/stm/main.c
index cdc4432c09..2085182c29 100644
--- a/stm/main.c
+++ b/stm/main.c
@@ -812,36 +812,36 @@ soft_reset:
 
     // add some functions to the python namespace
     {
-        rt_store_name(qstr_from_str_static("help"), rt_make_function_0(pyb_help));
+        rt_store_name(qstr_from_str_static("help"), rt_make_function_n(0, pyb_help));
 
         mp_obj_t m = mp_obj_new_module(qstr_from_str_static("pyb"));
-        rt_store_attr(m, qstr_from_str_static("info"), rt_make_function_0(pyb_info));
-        rt_store_attr(m, qstr_from_str_static("sd_test"), rt_make_function_0(pyb_sd_test));
-        rt_store_attr(m, qstr_from_str_static("stop"), rt_make_function_0(pyb_stop));
-        rt_store_attr(m, qstr_from_str_static("standby"), rt_make_function_0(pyb_standby));
-        rt_store_attr(m, qstr_from_str_static("source_dir"), rt_make_function_1(pyb_source_dir));
-        rt_store_attr(m, qstr_from_str_static("main"), rt_make_function_1(pyb_main));
-        rt_store_attr(m, qstr_from_str_static("sync"), rt_make_function_0(pyb_sync));
-        rt_store_attr(m, qstr_from_str_static("gc"), rt_make_function_0(pyb_gc));
-        rt_store_attr(m, qstr_from_str_static("delay"), rt_make_function_1(pyb_delay));
-        rt_store_attr(m, qstr_from_str_static("led"), rt_make_function_1(pyb_led));
+        rt_store_attr(m, qstr_from_str_static("info"), rt_make_function_n(0, pyb_info));
+        rt_store_attr(m, qstr_from_str_static("sd_test"), rt_make_function_n(0, pyb_sd_test));
+        rt_store_attr(m, qstr_from_str_static("stop"), rt_make_function_n(0, pyb_stop));
+        rt_store_attr(m, qstr_from_str_static("standby"), rt_make_function_n(0, pyb_standby));
+        rt_store_attr(m, qstr_from_str_static("source_dir"), rt_make_function_n(1, pyb_source_dir));
+        rt_store_attr(m, qstr_from_str_static("main"), rt_make_function_n(1, pyb_main));
+        rt_store_attr(m, qstr_from_str_static("sync"), rt_make_function_n(0, pyb_sync));
+        rt_store_attr(m, qstr_from_str_static("gc"), rt_make_function_n(0, pyb_gc));
+        rt_store_attr(m, qstr_from_str_static("delay"), rt_make_function_n(1, pyb_delay));
+        rt_store_attr(m, qstr_from_str_static("led"), rt_make_function_n(1, pyb_led));
         rt_store_attr(m, qstr_from_str_static("switch"), (mp_obj_t)&pyb_switch_obj);
-        rt_store_attr(m, qstr_from_str_static("servo"), rt_make_function_2(pyb_servo_set));
-        rt_store_attr(m, qstr_from_str_static("pwm"), rt_make_function_2(pyb_pwm_set));
+        rt_store_attr(m, qstr_from_str_static("servo"), rt_make_function_n(2, pyb_servo_set));
+        rt_store_attr(m, qstr_from_str_static("pwm"), rt_make_function_n(2, pyb_pwm_set));
         rt_store_attr(m, qstr_from_str_static("accel"), (mp_obj_t)&pyb_mma_read_obj);
         rt_store_attr(m, qstr_from_str_static("mma_read"), (mp_obj_t)&pyb_mma_read_all_obj);
         rt_store_attr(m, qstr_from_str_static("mma_mode"), (mp_obj_t)&pyb_mma_write_mode_obj);
-        rt_store_attr(m, qstr_from_str_static("hid"), rt_make_function_1(pyb_hid_send_report));
-        rt_store_attr(m, qstr_from_str_static("time"), rt_make_function_0(pyb_rtc_read));
-        rt_store_attr(m, qstr_from_str_static("rand"), rt_make_function_0(pyb_rng_get));
-        rt_store_attr(m, qstr_from_str_static("Led"), rt_make_function_1(pyb_Led));
-        rt_store_attr(m, qstr_from_str_static("Servo"), rt_make_function_1(pyb_Servo));
-        rt_store_attr(m, qstr_from_str_static("I2C"), rt_make_function_2(pyb_I2C));
+        rt_store_attr(m, qstr_from_str_static("hid"), rt_make_function_n(1, pyb_hid_send_report));
+        rt_store_attr(m, qstr_from_str_static("time"), rt_make_function_n(0, pyb_rtc_read));
+        rt_store_attr(m, qstr_from_str_static("rand"), rt_make_function_n(0, pyb_rng_get));
+        rt_store_attr(m, qstr_from_str_static("Led"), rt_make_function_n(1, pyb_Led));
+        rt_store_attr(m, qstr_from_str_static("Servo"), rt_make_function_n(1, pyb_Servo));
+        rt_store_attr(m, qstr_from_str_static("I2C"), rt_make_function_n(2, pyb_I2C));
         rt_store_attr(m, qstr_from_str_static("gpio"), (mp_obj_t)&pyb_gpio_obj);
-        rt_store_attr(m, qstr_from_str_static("Usart"), rt_make_function_2(pyb_Usart));
+        rt_store_attr(m, qstr_from_str_static("Usart"), rt_make_function_n(2, pyb_Usart));
         rt_store_name(qstr_from_str_static("pyb"), m);
 
-        rt_store_name(qstr_from_str_static("open"), rt_make_function_2(pyb_io_open));
+        rt_store_name(qstr_from_str_static("open"), rt_make_function_n(2, pyb_io_open));
     }
 
     // print a message to the LCD
diff --git a/stm/pybwlan.c b/stm/pybwlan.c
index 09d642d9c8..91d71a652b 100644
--- a/stm/pybwlan.c
+++ b/stm/pybwlan.c
@@ -357,11 +357,11 @@ void pyb_wlan_init(void) {
 
     mp_obj_t m = mp_obj_new_module(qstr_from_str_static("wlan"));
     rt_store_attr(m, qstr_from_str_static("connect"), rt_make_function_var(0, pyb_wlan_connect));
-    rt_store_attr(m, qstr_from_str_static("disconnect"), rt_make_function_0(pyb_wlan_disconnect));
-    rt_store_attr(m, qstr_from_str_static("ip"), rt_make_function_0(pyb_wlan_get_ip));
-    rt_store_attr(m, qstr_from_str_static("get_host"), rt_make_function_1(pyb_wlan_get_host));
-    rt_store_attr(m, qstr_from_str_static("http_get"), rt_make_function_2(pyb_wlan_http_get));
-    rt_store_attr(m, qstr_from_str_static("serve"), rt_make_function_0(pyb_wlan_serve));
+    rt_store_attr(m, qstr_from_str_static("disconnect"), rt_make_function_n(0, pyb_wlan_disconnect));
+    rt_store_attr(m, qstr_from_str_static("ip"), rt_make_function_n(0, pyb_wlan_get_ip));
+    rt_store_attr(m, qstr_from_str_static("get_host"), rt_make_function_n(1, pyb_wlan_get_host));
+    rt_store_attr(m, qstr_from_str_static("http_get"), rt_make_function_n(2, pyb_wlan_http_get));
+    rt_store_attr(m, qstr_from_str_static("serve"), rt_make_function_n(0, pyb_wlan_serve));
     rt_store_name(qstr_from_str_static("wlan"), m);
 }
 
diff --git a/stm/timer.c b/stm/timer.c
index 2605d4b4bc..c665a461d0 100644
--- a/stm/timer.c
+++ b/stm/timer.c
@@ -72,10 +72,10 @@ void timer_init(void) {
 
     // Python interface
     mp_obj_t m = mp_obj_new_module(qstr_from_str_static("timer"));
-    rt_store_attr(m, qstr_from_str_static("callback"), rt_make_function_1(timer_py_set_callback));
-    rt_store_attr(m, qstr_from_str_static("period"), rt_make_function_1(timer_py_set_period));
-    rt_store_attr(m, qstr_from_str_static("prescaler"), rt_make_function_1(timer_py_set_prescaler));
-    rt_store_attr(m, qstr_from_str_static("value"), rt_make_function_0(timer_py_get_value));
+    rt_store_attr(m, qstr_from_str_static("callback"), rt_make_function_n(1, timer_py_set_callback));
+    rt_store_attr(m, qstr_from_str_static("period"), rt_make_function_n(1, timer_py_set_period));
+    rt_store_attr(m, qstr_from_str_static("prescaler"), rt_make_function_n(1, timer_py_set_prescaler));
+    rt_store_attr(m, qstr_from_str_static("value"), rt_make_function_n(0, timer_py_get_value));
     rt_store_name(qstr_from_str_static("timer"), m);
 }