diff --git a/litex_boards/targets/mnt_rkx7.py b/litex_boards/targets/mnt_rkx7.py
index 14336b2..dd94136 100755
--- a/litex_boards/targets/mnt_rkx7.py
+++ b/litex_boards/targets/mnt_rkx7.py
@@ -47,7 +47,7 @@ class _CRG(Module):
 # BaseSoC ------------------------------------------------------------------------------------------
 
 class BaseSoC(SoCCore):
-    def __init__(self, sys_clk_freq=int(125e6), with_ethernet=False, with_etherbone=False,
+    def __init__(self, sys_clk_freq=int(100e6), with_ethernet=False, with_etherbone=False,
         with_spi_flash=False, **kwargs):
         platform = mnt_rkx7.Platform()
 
@@ -99,7 +99,7 @@ def main():
     parser = argparse.ArgumentParser(description="LiteX SoC on MNT-RKX7")
     parser.add_argument("--build",          action="store_true", help="Build bitstream")
     parser.add_argument("--load",           action="store_true", help="Load bitstream")
-    parser.add_argument("--sys-clk-freq",   default=125e6,       help="System clock frequency (default: 125MHz)")
+    parser.add_argument("--sys-clk-freq",   default=100e6,       help="System clock frequency (default: 100MHz)")
     parser.add_argument("--with-spi-flash", action="store_true", help="Enable SPI Flash (MMAPed)")
     sdopts = parser.add_mutually_exclusive_group()
     sdopts.add_argument("--with-spi-sdcard",     action="store_true",              help="Enable SPI-mode SDCard support")