diff --git a/cores/arduino/ch32/pinmap.c b/cores/arduino/ch32/pinmap.c
index f58dc22..8e5f510 100644
--- a/cores/arduino/ch32/pinmap.c
+++ b/cores/arduino/ch32/pinmap.c
@@ -166,7 +166,11 @@ void pin_function(PinName pin, int function)
 
   }
 
+#if defined(CH32X035)
+  GPIO_InitStructure.GPIO_Pin = ch_pinx; // fixed by Ngo Hung Cuong: pin_16, 17, ..., 23
+#else
   GPIO_InitStructure.GPIO_Pin = (uint16_t) ch_pinx;
+#endif  
   GPIO_Init(gpio, &GPIO_InitStructure);
 }