diff --git a/artiq/firmware/libboard_artiq/si5324.rs b/artiq/firmware/libboard_artiq/si5324.rs
index 22b452d54..ee3feb1a1 100644
--- a/artiq/firmware/libboard_artiq/si5324.rs
+++ b/artiq/firmware/libboard_artiq/si5324.rs
@@ -28,7 +28,7 @@ pub struct FrequencySettings {
     pub n31: u32,
     pub n32: u32,
     pub bwsel: u8,
-    pub crystal_ref: bool
+    pub crystal_as_ckin2: bool
 }
 
 pub enum Input {
@@ -83,7 +83,7 @@ fn map_frequency_settings(settings: &FrequencySettings) -> Result<FrequencySetti
         n31: settings.n31 - 1,
         n32: settings.n32 - 1,
         bwsel: settings.bwsel,
-        crystal_ref: settings.crystal_ref
+        crystal_as_ckin2: settings.crystal_as_ckin2
     };
     Ok(r)
 }
@@ -223,7 +223,7 @@ pub fn setup(settings: &FrequencySettings, input: Input) -> Result<()> {
     };
 
     init()?;
-    if settings.crystal_ref {
+    if settings.crystal_as_ckin2 {
         write(0,   read(0)? | 0x40)?;                     // FREE_RUN=1
     }
     write(2,   (read(2)? & 0x0f) | (s.bwsel << 4))?;
diff --git a/artiq/firmware/runtime/rtio_clocking.rs b/artiq/firmware/runtime/rtio_clocking.rs
index da4d8ad92..ffe1de082 100644
--- a/artiq/firmware/runtime/rtio_clocking.rs
+++ b/artiq/firmware/runtime/rtio_clocking.rs
@@ -142,7 +142,7 @@ fn setup_si5324_as_synthesizer(cfg: RtioClock) {
                     n31    : 6,
                     n32    : 6,
                     bwsel  : 4,
-                    crystal_ref: false
+                    crystal_as_ckin2: false
                 },
                 SI5324_EXT_INPUT
             )
@@ -158,7 +158,7 @@ fn setup_si5324_as_synthesizer(cfg: RtioClock) {
                     n31    : 52,
                     n32    : 52,
                     bwsel  : 4,
-                    crystal_ref: false
+                    crystal_as_ckin2: false
                 },
                 SI5324_EXT_INPUT
             )
@@ -174,7 +174,7 @@ fn setup_si5324_as_synthesizer(cfg: RtioClock) {
                     n31    : 63,
                     n32    : 63,
                     bwsel  : 4,
-                    crystal_ref: false
+                    crystal_as_ckin2: false
                 },
                 SI5324_EXT_INPUT
             )
@@ -190,7 +190,7 @@ fn setup_si5324_as_synthesizer(cfg: RtioClock) {
                     n31    : 7139,
                     n32    : 7139,
                     bwsel  : 3,
-                    crystal_ref: true
+                    crystal_as_ckin2: true
                 },
                 si5324::Input::Ckin2
             )
@@ -206,7 +206,7 @@ fn setup_si5324_as_synthesizer(cfg: RtioClock) {
                     n31    : 7139,
                     n32    : 7139,
                     bwsel  : 3,
-                    crystal_ref: true
+                    crystal_as_ckin2: true
                 },
                 si5324::Input::Ckin2
             )
@@ -222,7 +222,7 @@ fn setup_si5324_as_synthesizer(cfg: RtioClock) {
                     n31    : 4565,
                     n32    : 4565,
                     bwsel  : 4,
-                    crystal_ref: true
+                    crystal_as_ckin2: true
                 },
                 si5324::Input::Ckin2
             )
@@ -238,7 +238,7 @@ fn setup_si5324_as_synthesizer(cfg: RtioClock) {
                     n31    : 4565,
                     n32    : 4565,
                     bwsel  : 4,
-                    crystal_ref: true
+                    crystal_as_ckin2: true
                 },
                 si5324::Input::Ckin2
             )
diff --git a/artiq/firmware/satman/main.rs b/artiq/firmware/satman/main.rs
index 7dde13f3f..72510d19c 100644
--- a/artiq/firmware/satman/main.rs
+++ b/artiq/firmware/satman/main.rs
@@ -436,7 +436,7 @@ const SI5324_SETTINGS: si5324::FrequencySettings
     n31    : 75,
     n32    : 75,
     bwsel  : 4,
-    crystal_ref: true
+    crystal_as_ckin2: true
 };
 
 #[cfg(all(has_si5324, rtio_frequency = "125.0"))]
@@ -449,7 +449,7 @@ const SI5324_SETTINGS: si5324::FrequencySettings
     n31    : 63,
     n32    : 63,
     bwsel  : 4,
-    crystal_ref: true
+    crystal_as_ckin2: true
 };
 
 #[cfg(all(has_si5324, rtio_frequency = "100.0"))]
@@ -462,7 +462,7 @@ const SI5324_SETTINGS: si5324::FrequencySettings
     n31    : 50,
     n32    : 50,
     bwsel  : 4,
-    crystal_ref: true
+    crystal_as_ckin2: true
 };
 
 #[no_mangle]