diff --git a/ports/stm32/boards/make-pins.py b/ports/stm32/boards/make-pins.py
index 1b89fd6415..6f8a0a659d 100755
--- a/ports/stm32/boards/make-pins.py
+++ b/ports/stm32/boards/make-pins.py
@@ -215,7 +215,7 @@ class Stm32Pin(boardgen.Pin):
     def validate_cpu_pin_name(cpu_pin_name):
         boardgen.Pin.validate_cpu_pin_name(cpu_pin_name)
 
-        if not re.match("P[A-K][0-9]+(_C)?$", cpu_pin_name):
+        if not re.match("P[A-O][0-9]+(_C)?$", cpu_pin_name):
             raise boardgen.PinGeneratorError("Invalid cpu pin name '{}'".format(cpu_pin_name))
 
 
diff --git a/ports/stm32/pin_defs_stm32.h b/ports/stm32/pin_defs_stm32.h
index 6c67b64924..645ec5b2df 100644
--- a/ports/stm32/pin_defs_stm32.h
+++ b/ports/stm32/pin_defs_stm32.h
@@ -39,6 +39,10 @@ enum {
     PORT_I,
     PORT_J,
     PORT_K,
+    PORT_L,
+    PORT_M,
+    PORT_N,
+    PORT_O,
 };
 
 // Must have matching entries in SUPPORTED_FN in boards/make-pins.py