diff --git a/artiq/runtime.rs/libksupport/api.rs b/artiq/runtime.rs/libksupport/api.rs
index aa6483bbd..81c4d75df 100644
--- a/artiq/runtime.rs/libksupport/api.rs
+++ b/artiq/runtime.rs/libksupport/api.rs
@@ -105,13 +105,16 @@ static mut API: &'static [(&'static str, *const ())] = &[
     api!(rtio_input_timestamp),
     api!(rtio_input_data),
 
-// #if ((defined CONFIG_RTIO_DDS_COUNT) && (CONFIG_RTIO_DDS_COUNT > 0))
+    #[cfg(rtio_dds_count)]
     api!(dds_init),
+    #[cfg(rtio_dds_count)]
     api!(dds_init_sync),
+    #[cfg(rtio_dds_count)]
     api!(dds_batch_enter),
+    #[cfg(rtio_dds_count)]
     api!(dds_batch_exit),
+    #[cfg(rtio_dds_count)]
     api!(dds_set),
-// #endif
 
     api!(i2c_init),
     api!(i2c_start),
diff --git a/artiq/runtime.rs/src/lib.rs b/artiq/runtime.rs/src/lib.rs
index e661c427f..48efd5d0d 100644
--- a/artiq/runtime.rs/src/lib.rs
+++ b/artiq/runtime.rs/src/lib.rs
@@ -75,6 +75,7 @@ mod rpc_proto;
 
 mod kernel;
 mod session;
+#[cfg(has_rtio_moninj)]
 mod moninj;
 #[cfg(has_rtio_analyzer)]
 mod analyzer;
@@ -109,6 +110,7 @@ pub unsafe extern fn rust_main() {
 
         let mut scheduler = sched::Scheduler::new();
         scheduler.spawner().spawn(16384, session::thread);
+        #[cfg(has_rtio_moninj)]
         scheduler.spawner().spawn(4096, moninj::thread);
         #[cfg(has_rtio_analyzer)]
         scheduler.spawner().spawn(4096, analyzer::thread);
diff --git a/artiq/runtime/rtio.c b/artiq/runtime/rtio.c
index 09f71d9d4..ac5168224 100644
--- a/artiq/runtime/rtio.c
+++ b/artiq/runtime/rtio.c
@@ -124,6 +124,7 @@ unsigned int rtio_input_data(int channel)
 
 void rtio_log_va(long long int timestamp, const char *fmt, va_list args)
 {
+#ifdef CONFIG_RTIO_LOG_CHANNEL
     // This executes on the kernel CPU's stack, which is specifically designed
     // for allocation of this kind of massive buffers.
     int   len = vsnprintf(NULL, 0, fmt, args);
@@ -152,6 +153,7 @@ void rtio_log_va(long long int timestamp, const char *fmt, va_list args)
             i = 0;
         }
     }
+#endif
 }
 
 void rtio_log(long long int timestamp, const char *fmt, ...)