diff --git a/Marlin/src/HAL/STM32F1/HAL_SPI.cpp b/Marlin/src/HAL/STM32F1/HAL_SPI.cpp
index 550a79deae..76b1c3e246 100644
--- a/Marlin/src/HAL/STM32F1/HAL_SPI.cpp
+++ b/Marlin/src/HAL/STM32F1/HAL_SPI.cpp
@@ -110,7 +110,7 @@ void spiInit(uint8_t spiRate) {
  * @details
  */
 uint8_t spiRec() {
-  uint8_t returnByte = SPI.transfer(ff);
+  uint8_t returnByte = SPI.transfer(0xFF);
   return returnByte;
 }
 
@@ -154,7 +154,7 @@ void spiSendBlock(uint8_t token, const uint8_t* buf) {
 #if ENABLED(SPI_EEPROM)
 
 // Read single byte from specified SPI channel
-uint8_t spiRec(uint32_t chan) { return SPI.transfer(ff); }
+uint8_t spiRec(uint32_t chan) { return SPI.transfer(0xFF); }
 
 // Write single byte to specified SPI channel
 void spiSend(uint32_t chan, byte b) { SPI.send(b); }
diff --git a/Marlin/src/libs/W25Qxx.cpp b/Marlin/src/libs/W25Qxx.cpp
index 9abe45fbaf..03e002f66f 100644
--- a/Marlin/src/libs/W25Qxx.cpp
+++ b/Marlin/src/libs/W25Qxx.cpp
@@ -80,16 +80,14 @@ void W25QXXFlash::init(uint8_t spiRate) {
  * @brief  Receive a single byte from the SPI port.
  *
  * @return Byte received
- *
- * @details
  */
 uint8_t W25QXXFlash::spi_flash_Rec() {
-  uint8_t returnByte = SPI.transfer(ff);
+  const uint8_t returnByte = SPI.transfer(0xFF);
   return returnByte;
 }
 
 uint8_t W25QXXFlash::spi_flash_read_write_byte(uint8_t data) {
-  uint8_t returnByte = SPI.transfer(data);
+  const uint8_t returnByte = SPI.transfer(data);
   return returnByte;
 }