diff --git a/ports/mimxrt/Makefile b/ports/mimxrt/Makefile
index 63cba7d7a67c76225ae4f2b056864dfd1028bec5..8cb46245aec97719875627d01b1ba0449bd99872 100644
--- a/ports/mimxrt/Makefile
+++ b/ports/mimxrt/Makefile
@@ -397,6 +397,10 @@ CFLAGS += \
 	-DFSL_FEATURE_PHYKSZ8081_USE_RMII50M_MODE=1
 endif
 
+ifdef MICROPY_HW_FLASH_CLK
+	CFLAGS += -DMICROPY_HW_FLASH_CLK=$(MICROPY_HW_FLASH_CLK)
+endif
+
 CFLAGS += $(CFLAGS_EXTRA)
 
 MPY_CROSS_FLAGS += -march=armv7m
diff --git a/ports/mimxrt/hal/qspi_hyper_flash_config.c b/ports/mimxrt/hal/qspi_hyper_flash_config.c
index f5ffbe8413a7dc353989bf9f157668c8f6605409..aaf2e923c162d2437800f1d87fdd341397543dc7 100644
--- a/ports/mimxrt/hal/qspi_hyper_flash_config.c
+++ b/ports/mimxrt/hal/qspi_hyper_flash_config.c
@@ -22,6 +22,10 @@ __attribute__((section(".boot_hdr.conf")))
 #pragma location = ".boot_hdr.conf"
 #endif
 
+#ifndef MICROPY_HW_FLASH_CLK
+#define MICROPY_HW_FLASH_CLK kFlexSpiSerialClk_133MHz
+#endif
+
 const flexspi_nor_config_t qspiflash_config = {
     .memConfig =
     {
@@ -36,7 +40,7 @@ const flexspi_nor_config_t qspiflash_config = {
             (1u << kFlexSpiMiscOffset_DdrModeEnable) | (1u << kFlexSpiMiscOffset_WordAddressableEnable) |
             (1u << kFlexSpiMiscOffset_SafeConfigFreqEnable) | (1u << kFlexSpiMiscOffset_DiffClkEnable),
         .sflashPadType = kSerialFlash_8Pads,
-        .serialClkFreq = kFlexSpiSerialClk_133MHz,
+        .serialClkFreq = MICROPY_HW_FLASH_CLK,
         .sflashA1Size = MICROPY_HW_FLASH_SIZE,
         .dataValidTime = {16u, 16u},
         .lookupTable =
diff --git a/ports/mimxrt/hal/qspi_nor_flash_config.c b/ports/mimxrt/hal/qspi_nor_flash_config.c
index a6bbd624ed53471893611e3c4adda0fdbd19d378..a8040737e51b02c7440644f7b418a393ab08c9b5 100644
--- a/ports/mimxrt/hal/qspi_nor_flash_config.c
+++ b/ports/mimxrt/hal/qspi_nor_flash_config.c
@@ -28,6 +28,10 @@ __attribute__((section(".boot_hdr.conf")))
 #define MICROPY_HW_FLASH_DQS kFlexSPIReadSampleClk_LoopbackFromDqsPad
 #endif
 
+#ifndef MICROPY_HW_FLASH_CLK
+#define MICROPY_HW_FLASH_CLK kFlexSpiSerialClk_100MHz
+#endif
+
 const flexspi_nor_config_t qspiflash_config = {
     .memConfig =
     {
@@ -48,7 +52,7 @@ const flexspi_nor_config_t qspiflash_config = {
         // Enable DDR mode, Wordaddassable, Safe configuration, Differential clock
         .deviceType = kFlexSpiDeviceType_SerialNOR,
         .sflashPadType = kSerialFlash_4Pads,
-        .serialClkFreq = kFlexSpiSerialClk_100MHz,
+        .serialClkFreq = MICROPY_HW_FLASH_CLK,
         .sflashA1Size = MICROPY_HW_FLASH_SIZE,
         .lookupTable =
         {