diff --git a/artiq/gateware/eem.py b/artiq/gateware/eem.py
index 203656638..fad54969f 100644
--- a/artiq/gateware/eem.py
+++ b/artiq/gateware/eem.py
@@ -24,7 +24,7 @@ class _EEM:
     def add_extension(cls, target, eem, *args, **kwargs):
         name = cls.__name__
         target.platform.add_extension(cls.io(eem, *args, **kwargs))
-        print("{} (EEM{}) starting at RTIO channel {}"
+        print("{} (EEM{}) starting at RTIO channel 0x{:06x}"
               .format(name, eem, len(target.rtio_channels)))
 
 
diff --git a/artiq/gateware/targets/kasli_generic.py b/artiq/gateware/targets/kasli_generic.py
index 0aacecd21..c7e74064f 100755
--- a/artiq/gateware/targets/kasli_generic.py
+++ b/artiq/gateware/targets/kasli_generic.py
@@ -133,7 +133,7 @@ class GenericStandalone(StandaloneBase):
         self.rtio_channels = []
         add_peripherals(self, description["peripherals"])
         for i in (1, 2):
-            print("SFP LED at RTIO channel {}".format(len(self.rtio_channels)))
+            print("SFP LED at RTIO channel 0x{:06x}".format(len(self.rtio_channels)))
             sfp_ctl = self.platform.request("sfp_ctl", i)
             phy = ttl_simple.Output(sfp_ctl.led)
             self.submodules += phy