diff --git a/locale/circuitpython.pot b/locale/circuitpython.pot
index 6114dcfaea..aa4f0f1f56 100644
--- a/locale/circuitpython.pot
+++ b/locale/circuitpython.pot
@@ -66,6 +66,14 @@ msgid ""
 "%d address pins, %d rgb pins and %d tiles indicate a height of %d, not %d"
 msgstr ""
 
+#: shared-bindings/microcontroller/Pin.c
+msgid "%q and %q contain duplicate pins"
+msgstr ""
+
+#: shared-bindings/microcontroller/Pin.c
+msgid "%q contains duplicate pins"
+msgstr ""
+
 #: ports/atmel-samd/common-hal/sdioio/SDCard.c
 msgid "%q failure: %d"
 msgstr ""
diff --git a/ports/stm/boards/stm32f411ce_blackpill_with_flash/mpconfigboard.mk b/ports/stm/boards/stm32f411ce_blackpill_with_flash/mpconfigboard.mk
index e095d69403..9da7163743 100644
--- a/ports/stm/boards/stm32f411ce_blackpill_with_flash/mpconfigboard.mk
+++ b/ports/stm/boards/stm32f411ce_blackpill_with_flash/mpconfigboard.mk
@@ -16,3 +16,6 @@ MCU_PACKAGE = UFQFPN48
 
 LD_COMMON = boards/common_default.ld
 LD_FILE = boards/STM32F411_nofs.ld
+
+# Too big for the flash
+CIRCUITPY_ULAB = 0
diff --git a/shared-bindings/keypad/KeyMatrix.c b/shared-bindings/keypad/KeyMatrix.c
index 0b854ef475..dbb4ac6822 100644
--- a/shared-bindings/keypad/KeyMatrix.c
+++ b/shared-bindings/keypad/KeyMatrix.c
@@ -90,6 +90,8 @@ STATIC mp_obj_t keypad_keymatrix_make_new(const mp_obj_type_t *type, size_t n_ar
     mcu_pin_obj_t *row_pins_array[num_row_pins];
     mcu_pin_obj_t *column_pins_array[num_column_pins];
 
+    validate_no_duplicate_pins_2(row_pins, column_pins, MP_QSTR_row_pins, MP_QSTR_column_pins);
+
     for (size_t row = 0; row < num_row_pins; row++) {
         mcu_pin_obj_t *pin =
             validate_obj_is_free_pin(mp_obj_subscr(row_pins, MP_OBJ_NEW_SMALL_INT(row), MP_OBJ_SENTINEL));
diff --git a/shared-bindings/keypad/Keys.c b/shared-bindings/keypad/Keys.c
index d616bcff84..dc533a2e2b 100644
--- a/shared-bindings/keypad/Keys.c
+++ b/shared-bindings/keypad/Keys.c
@@ -78,6 +78,7 @@ STATIC mp_obj_t keypad_keys_make_new(const mp_obj_type_t *type, size_t n_args, c
     mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
 
     mp_obj_t pins = args[ARG_pins].u_obj;
+    validate_no_duplicate_pins(pins, MP_QSTR_row_pins);
     // mp_obj_len() will be >= 0.
     const size_t num_pins = (size_t)MP_OBJ_SMALL_INT_VALUE(mp_obj_len(pins));
 
diff --git a/shared-bindings/microcontroller/Pin.c b/shared-bindings/microcontroller/Pin.c
index acb1710f3d..78c1c90f4d 100644
--- a/shared-bindings/microcontroller/Pin.c
+++ b/shared-bindings/microcontroller/Pin.c
@@ -105,6 +105,45 @@ mcu_pin_obj_t *validate_obj_is_free_pin(mp_obj_t obj) {
     return pin;
 }
 
+// Validate every element in the list is a unique pin
+void validate_no_duplicate_pins(mp_obj_t seq, qstr arg_name) {
+    const size_t num_pins = (size_t)MP_OBJ_SMALL_INT_VALUE(mp_obj_len(seq));
+
+    for (size_t pin_cnt = 0; pin_cnt < num_pins; pin_cnt++) {
+        mp_obj_t pin1_obj = mp_obj_subscr(seq, MP_OBJ_NEW_SMALL_INT(pin_cnt), MP_OBJ_SENTINEL);
+        mcu_pin_obj_t *pin1 = validate_obj_is_pin(pin1_obj);
+
+        for (size_t pin_cnt_2 = pin_cnt + 1; pin_cnt_2 < num_pins; pin_cnt_2++) {
+            mp_obj_t pin2_obj = mp_obj_subscr(seq, MP_OBJ_NEW_SMALL_INT(pin_cnt_2), MP_OBJ_SENTINEL);
+            mcu_pin_obj_t *pin2 = validate_obj_is_pin(pin2_obj);
+            if (pin1 == pin2) {
+                mp_raise_TypeError_varg(translate("%q contains duplicate pins"), arg_name);
+            }
+        }
+    }
+}
+
+void validate_no_duplicate_pins_2(mp_obj_t seq1, mp_obj_t seq2, qstr arg_name1, qstr arg_name2) {
+    const size_t num_pins_1 = (size_t)MP_OBJ_SMALL_INT_VALUE(mp_obj_len(seq1));
+    const size_t num_pins_2 = (size_t)MP_OBJ_SMALL_INT_VALUE(mp_obj_len(seq2));
+
+    validate_no_duplicate_pins(seq1, arg_name1);
+    validate_no_duplicate_pins(seq2, arg_name2);
+
+    for (size_t pin_cnt_1 = 0; pin_cnt_1 < num_pins_1; pin_cnt_1++) {
+        mp_obj_t pin1_obj = mp_obj_subscr(seq1, MP_OBJ_NEW_SMALL_INT(pin_cnt_1), MP_OBJ_SENTINEL);
+        mcu_pin_obj_t *pin1 = validate_obj_is_pin(pin1_obj);
+
+        for (size_t pin_cnt_2 = 0; pin_cnt_2 < num_pins_2; pin_cnt_2++) {
+            mp_obj_t pin2_obj = mp_obj_subscr(seq2, MP_OBJ_NEW_SMALL_INT(pin_cnt_2), MP_OBJ_SENTINEL);
+            mcu_pin_obj_t *pin2 = validate_obj_is_pin(pin2_obj);
+            if (pin1 == pin2) {
+                mp_raise_TypeError_varg(translate("%q and %q contain duplicate pins"), arg_name1, arg_name2);
+            }
+        }
+    }
+}
+
 // Validate every element in the list to be a free pin.
 void validate_list_is_free_pins(qstr what, mcu_pin_obj_t **pins_out, mp_int_t max_pins, mp_obj_t seq, uint8_t *count_out) {
     mp_int_t len = MP_OBJ_SMALL_INT_VALUE(mp_obj_len(seq));
diff --git a/shared-bindings/microcontroller/Pin.h b/shared-bindings/microcontroller/Pin.h
index 44019ff267..a8ac6eeb1c 100644
--- a/shared-bindings/microcontroller/Pin.h
+++ b/shared-bindings/microcontroller/Pin.h
@@ -37,6 +37,8 @@ mcu_pin_obj_t *validate_obj_is_pin(mp_obj_t obj);
 mcu_pin_obj_t *validate_obj_is_pin_or_none(mp_obj_t obj);
 mcu_pin_obj_t *validate_obj_is_free_pin(mp_obj_t obj);
 mcu_pin_obj_t *validate_obj_is_free_pin_or_none(mp_obj_t obj);
+void validate_no_duplicate_pins(mp_obj_t seq, qstr arg_name);
+void validate_no_duplicate_pins_2(mp_obj_t seq1, mp_obj_t seq2, qstr arg_name1, qstr arg_name2);
 void validate_list_is_free_pins(qstr what, mcu_pin_obj_t **pins_out, mp_int_t max_pins, mp_obj_t seq, uint8_t *count_out);
 void validate_pins(qstr what, uint8_t *pin_nos, mp_int_t max_pins, mp_obj_t seq, uint8_t *count_out);