diff --git a/code/approx.c b/code/approx.c
index cc6f91e1..7e912387 100644
--- a/code/approx.c
+++ b/code/approx.c
@@ -22,7 +22,7 @@
 const mp_obj_float_t xtolerance = {{&mp_type_float}, 2.4e-7};
 const mp_obj_float_t rtolerance = {{&mp_type_float}, 0.0};
 
-mp_float_t approx_python_call(const mp_obj_type_t *type, mp_obj_t fun, mp_float_t x, mp_obj_t *fargs, uint8_t nparams) {
+STATIC mp_float_t approx_python_call(const mp_obj_type_t *type, mp_obj_t fun, mp_float_t x, mp_obj_t *fargs, uint8_t nparams) {
 	// Helper function for calculating the value of f(x, a, b, c, ...), 
 	// where f is defined in python. Takes a float, returns a float.
     // The array of mp_obj_t type must be supplied, as must the number of parameters (a, b, c...) in nparams
@@ -30,7 +30,7 @@ mp_float_t approx_python_call(const mp_obj_type_t *type, mp_obj_t fun, mp_float_
 	return mp_obj_get_float(type->call(fun, nparams+1, 0, fargs));
 }
 
-mp_obj_t approx_bisect(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+STATIC mp_obj_t approx_bisect(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
 	// Simple bisection routine
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_rom_obj = mp_const_none } },
@@ -75,7 +75,7 @@ mp_obj_t approx_bisect(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_arg
 
 MP_DEFINE_CONST_FUN_OBJ_KW(approx_bisect_obj, 3, approx_bisect);
 
-mp_obj_t approx_newton(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+STATIC mp_obj_t approx_newton(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
 	// this is actually the secant method, as the first derivative of the function 
 	// is not accepted as an argument. The function whose root we want to solve for 
 	// must depend on a single variable without parameters, i.e., f(x)
@@ -113,7 +113,7 @@ mp_obj_t approx_newton(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_arg
 
 MP_DEFINE_CONST_FUN_OBJ_KW(approx_newton_obj, 2, approx_newton);
 
-mp_obj_t approx_fmin(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+STATIC mp_obj_t approx_fmin(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
 	// downhill simplex method in 1D
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_rom_obj = mp_const_none } },
@@ -311,7 +311,7 @@ MP_DEFINE_CONST_FUN_OBJ_KW(approx_curve_fit_obj, 2, approx_curve_fit);
 
 #endif
 
-mp_obj_t approx_interp(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+STATIC mp_obj_t approx_interp(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_rom_obj = mp_const_none } },
         { MP_QSTR_, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_rom_obj = mp_const_none } },
diff --git a/code/ndarray.h b/code/ndarray.h
index 6635a3cb..285db971 100644
--- a/code/ndarray.h
+++ b/code/ndarray.h
@@ -28,6 +28,7 @@
 
 #if CIRCUITPY
 #define mp_obj_is_bool(o) (MP_OBJ_IS_TYPE((o), &mp_type_bool))
+#define mp_obj_is_int(x) (MP_OBJ_IS_INT((x)))
 #else
 #define translate(x) MP_ERROR_TEXT(x)
 #endif
diff --git a/code/vectorise.c b/code/vectorise.c
index 19140219..bd005fca 100644
--- a/code/vectorise.c
+++ b/code/vectorise.c
@@ -214,6 +214,8 @@ static mp_obj_t vectorise_arctan2(mp_obj_t x, mp_obj_t y) {
 MP_DEFINE_CONST_FUN_OBJ_2(vectorise_arctan2_obj, vectorise_arctan2);
 
 static mp_obj_t vectorise_vectorized_function_call(mp_obj_t self_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    (void) n_args;
+    (void) n_kw;
     vectorized_function_obj_t *self = MP_OBJ_TO_PTR(self_in);
     mp_obj_t avalue[1];
     mp_obj_t fvalue;