diff --git a/Marlin/src/HAL/STM32F1/MarlinSerial.cpp b/Marlin/src/HAL/STM32F1/MarlinSerial.cpp
index 568fc05d4185..8c68a2de7f29 100644
--- a/Marlin/src/HAL/STM32F1/MarlinSerial.cpp
+++ b/Marlin/src/HAL/STM32F1/MarlinSerial.cpp
@@ -28,7 +28,7 @@
 
 // Copied from ~/.platformio/packages/framework-arduinoststm32-maple/STM32F1/system/libmaple/usart_private.h
 // Changed to handle Emergency Parser
-static inline __always_inline void my_usart_irq(ring_buffer *rb, ring_buffer *wb, usart_reg_map *regs, MSerialT &serial) {
+static __always_inline void my_usart_irq(ring_buffer *rb, ring_buffer *wb, usart_reg_map *regs, MSerialT &serial) {
  /* Handle RXNEIE and TXEIE interrupts.
   * RXNE signifies availability of a byte in DR.
   *