diff --git a/artiq/firmware/runtime/main.rs b/artiq/firmware/runtime/main.rs
index 4e4011e40..364f801e9 100644
--- a/artiq/firmware/runtime/main.rs
+++ b/artiq/firmware/runtime/main.rs
@@ -110,18 +110,31 @@ fn startup() {
 #[cfg(si5324_free_running)]
 fn setup_si5324_free_running()
 {
-    // 125MHz output, from 10MHz CLKIN2 reference
+    // 125MHz output, from 100MHz CLKIN2 reference, 9 Hz
+    // FIXME: needs !FREE_RUN at address 0x00
     #[cfg(all(rtio_frequency = "125.0", si5324_ext_ref))]
     const SI5324_SETTINGS: board_artiq::si5324::FrequencySettings
         = board_artiq::si5324::FrequencySettings {
         n1_hs  : 10,
         nc1_ls : 4,
         n2_hs  : 10,
-        n2_ls  : 300,
-        n31    : 75,
-        n32    : 6,
+        n2_ls  : 260,
+        n31    : 65,
+        n32    : 52,
         bwsel  : 10
     };
+    // 125MHz output, from crystal, 7 Hz
+    #[cfg(all(rtio_frequency = "125.0", not(si5324_ext_ref)))]
+    const SI5324_SETTINGS: board_artiq::si5324::FrequencySettings
+        = board_artiq::si5324::FrequencySettings {
+        n1_hs  : 10,
+        nc1_ls : 4,
+        n2_hs  : 10,
+        n2_ls  : 19972,
+        n31    : 4993,
+        n32    : 4565,
+        bwsel  : 4
+    };
     // 150MHz output, from crystal
     #[cfg(all(rtio_frequency = "150.0", not(si5324_ext_ref)))]
     const SI5324_SETTINGS: board_artiq::si5324::FrequencySettings
diff --git a/artiq/gateware/targets/kasli.py b/artiq/gateware/targets/kasli.py
index 72b147064..2fd9058ae 100755
--- a/artiq/gateware/targets/kasli.py
+++ b/artiq/gateware/targets/kasli.py
@@ -230,7 +230,7 @@ class Opticlock(_StandaloneBase):
         _StandaloneBase.__init__(self, **kwargs)
 
         self.config["SI5324_FREE_RUNNING"] = None
-        self.config["SI5324_EXT_REF"] = None
+        # self.config["SI5324_EXT_REF"] = None
         self.config["RTIO_FREQUENCY"] = "125.0"
 
         platform = self.platform