diff --git a/docs/library/esp32.rst b/docs/library/esp32.rst
index 7701f43539..796dbbbc54 100644
--- a/docs/library/esp32.rst
+++ b/docs/library/esp32.rst
@@ -226,7 +226,7 @@ For more details see Espressif's `ESP-IDF RMT documentation.
     ``100``) and the output level to apply the carrier to (a boolean as per
     *idle_level*).
 
-.. method:: RMT.source_freq()
+.. classmethod:: RMT.source_freq()
 
     Returns the source clock frequency. Currently the source clock is not
     configurable so this will always return 80MHz.
diff --git a/ports/esp32/esp32_rmt.c b/ports/esp32/esp32_rmt.c
index f92af636f5..14caffddad 100644
--- a/ports/esp32/esp32_rmt.c
+++ b/ports/esp32/esp32_rmt.c
@@ -206,10 +206,11 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(esp32_rmt_deinit_obj, esp32_rmt_deinit);
 // Return the source frequency.
 // Currently only the APB clock (80MHz) can be used but it is possible other
 // clock sources will added in the future.
-STATIC mp_obj_t esp32_rmt_source_freq(mp_obj_t self_in) {
+STATIC mp_obj_t esp32_rmt_source_freq() {
     return mp_obj_new_int(APB_CLK_FREQ);
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(esp32_rmt_source_freq_obj, esp32_rmt_source_freq);
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(esp32_rmt_source_freq_obj, esp32_rmt_source_freq);
+STATIC MP_DEFINE_CONST_STATICMETHOD_OBJ(esp32_rmt_source_obj, MP_ROM_PTR(&esp32_rmt_source_freq_obj));
 
 // Return the clock divider.
 STATIC mp_obj_t esp32_rmt_clock_div(mp_obj_t self_in) {
@@ -357,7 +358,6 @@ STATIC MP_DEFINE_CONST_STATICMETHOD_OBJ(esp32_rmt_bitstream_channel_obj, MP_ROM_
 STATIC const mp_rom_map_elem_t esp32_rmt_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&esp32_rmt_deinit_obj) },
     { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&esp32_rmt_deinit_obj) },
-    { MP_ROM_QSTR(MP_QSTR_source_freq), MP_ROM_PTR(&esp32_rmt_source_freq_obj) },
     { MP_ROM_QSTR(MP_QSTR_clock_div), MP_ROM_PTR(&esp32_rmt_clock_div_obj) },
     { MP_ROM_QSTR(MP_QSTR_wait_done), MP_ROM_PTR(&esp32_rmt_wait_done_obj) },
     { MP_ROM_QSTR(MP_QSTR_loop), MP_ROM_PTR(&esp32_rmt_loop_obj) },
@@ -365,6 +365,9 @@ STATIC const mp_rom_map_elem_t esp32_rmt_locals_dict_table[] = {
 
     // Static methods
     { MP_ROM_QSTR(MP_QSTR_bitstream_channel), MP_ROM_PTR(&esp32_rmt_bitstream_channel_obj) },
+
+    // Class methods
+    { MP_ROM_QSTR(MP_QSTR_source_freq), MP_ROM_PTR(&esp32_rmt_source_obj) },
 };
 STATIC MP_DEFINE_CONST_DICT(esp32_rmt_locals_dict, esp32_rmt_locals_dict_table);