diff --git a/artiq/runtime/bridge.c b/artiq/runtime/bridge.c
index 78c47acfd..8d90864a1 100644
--- a/artiq/runtime/bridge.c
+++ b/artiq/runtime/bridge.c
@@ -18,6 +18,7 @@ static void rtio_output_blind(int channel, int addr, int data)
     rtio_o_we_write(1);
 }
 
+#if ((defined RTIO_DDS_COUNT) && (RTIO_DDS_COUNT > 0))
 static void dds_write(int bus_channel, int addr, int data)
 {
     rtio_output_blind(bus_channel, addr, data);
@@ -39,6 +40,7 @@ static int dds_read(int bus_channel, int addr)
     rtio_i_re_write(1);
     return r;
 }
+#endif
 
 static void send_ready(void)
 {
@@ -73,6 +75,7 @@ void bridge_main(void)
                 mailbox_acknowledge();
                 break;
             }
+#if ((defined RTIO_DDS_COUNT) && (RTIO_DDS_COUNT > 0))
             case MESSAGE_TYPE_BRG_DDS_SEL: {
                 struct msg_brg_dds_sel *msg;
 
@@ -119,6 +122,7 @@ void bridge_main(void)
                 mailbox_acknowledge();
                 break;
             }
+#endif /* RTIO_DDS_COUNT */
             default:
                 mailbox_acknowledge();
                 break;
diff --git a/artiq/runtime/dds.c b/artiq/runtime/dds.c
index 1a7d8f9f4..586243f4b 100644
--- a/artiq/runtime/dds.c
+++ b/artiq/runtime/dds.c
@@ -1,4 +1,7 @@
 #include <generated/csr.h>
+
+#if ((defined RTIO_DDS_COUNT) && (RTIO_DDS_COUNT > 0))
+
 #include <stdio.h>
 
 #include "artiq_personality.h"
@@ -221,3 +224,5 @@ void dds_set(long long int timestamp, int bus_channel, int channel,
                     ftw, pow, phase_mode, amplitude);
     }
 }
+
+#endif /* RTIO_DDS_COUNT */
diff --git a/artiq/runtime/dds.h b/artiq/runtime/dds.h
index 10fa3fffc..0a2a8ade4 100644
--- a/artiq/runtime/dds.h
+++ b/artiq/runtime/dds.h
@@ -5,6 +5,8 @@
 #include <generated/csr.h>
 #include <generated/mem.h>
 
+#if ((defined RTIO_DDS_COUNT) && (RTIO_DDS_COUNT > 0))
+
 /* Maximum number of commands in a batch */
 #define DDS_MAX_BATCH 16
 
@@ -60,4 +62,6 @@ void dds_batch_exit(void);
 void dds_set(long long int timestamp, int bus_channel, int channel,
     unsigned int ftw, unsigned int pow, int phase_mode, unsigned int amplitude);
 
+#endif /* RTIO_DDS_COUNT */
+
 #endif /* __DDS_H */
diff --git a/artiq/runtime/ksupport.c b/artiq/runtime/ksupport.c
index dde9bc3a2..049cc7ac6 100644
--- a/artiq/runtime/ksupport.c
+++ b/artiq/runtime/ksupport.c
@@ -118,10 +118,12 @@ static const struct symbol runtime_exports[] = {
     {"rtio_input_timestamp", &rtio_input_timestamp},
     {"rtio_input_data", &rtio_input_data},
 
+#if ((defined RTIO_DDS_COUNT) && (RTIO_DDS_COUNT > 0))
     {"dds_init", &dds_init},
     {"dds_batch_enter", &dds_batch_enter},
     {"dds_batch_exit", &dds_batch_exit},
     {"dds_set", &dds_set},
+#endif
 
     {"i2c_init", &i2c_init},
     {"i2c_start", &i2c_start},
diff --git a/artiq/runtime/moninj.c b/artiq/runtime/moninj.c
index 4a7c14205..9ad4ea79c 100644
--- a/artiq/runtime/moninj.c
+++ b/artiq/runtime/moninj.c
@@ -38,13 +38,15 @@ struct monitor_reply {
     long long int ttl_overrides;
     unsigned short int dds_rtio_first_channel;
     unsigned short int dds_channels_per_bus;
+#if ((defined RTIO_DDS_COUNT) && (RTIO_DDS_COUNT > 0))
     unsigned int dds_ftws[CONFIG_RTIO_DDS_COUNT*CONFIG_DDS_CHANNELS_PER_BUS];
+#endif
 } __attribute__((packed));
 
 static void moninj_monitor(const ip_addr_t *addr, u16_t port)
 {
     struct monitor_reply reply;
-    int i, j;
+    int i;
     struct pbuf *reply_p;
 
     reply.ttl_levels = 0;
@@ -66,6 +68,9 @@ static void moninj_monitor(const ip_addr_t *addr, u16_t port)
             reply.ttl_overrides |= 1LL << i;
     }
 
+#if ((defined RTIO_DDS_COUNT) && (RTIO_DDS_COUNT > 0))
+    int j;
+
     reply.dds_rtio_first_channel = CONFIG_RTIO_FIRST_DDS_CHANNEL;
     reply.dds_channels_per_bus = CONFIG_DDS_CHANNELS_PER_BUS;
     for(j=0;j<CONFIG_RTIO_DDS_COUNT;j++) {
@@ -76,6 +81,10 @@ static void moninj_monitor(const ip_addr_t *addr, u16_t port)
             reply.dds_ftws[CONFIG_DDS_CHANNELS_PER_BUS*j+i] = rtio_moninj_mon_value_read();
         }
     }
+#else
+    reply.dds_rtio_first_channel = 0;
+    reply.dds_channels_per_bus = 0;
+#endif
 
     reply_p = pbuf_alloc(PBUF_TRANSPORT, sizeof(struct monitor_reply), PBUF_RAM);
     if(!reply_p) {
diff --git a/artiq/runtime/test_mode.c b/artiq/runtime/test_mode.c
index 6bd057548..fe826fca6 100644
--- a/artiq/runtime/test_mode.c
+++ b/artiq/runtime/test_mode.c
@@ -108,6 +108,8 @@ static void ttlo(char *n, char *value)
     brg_ttlo(n2, value2);
 }
 
+#if ((defined RTIO_DDS_COUNT) && (RTIO_DDS_COUNT > 0))
+
 static int bus_channel = CONFIG_RTIO_FIRST_DDS_CHANNEL;
 
 static void ddsbus(char *n)
@@ -360,6 +362,7 @@ static void ddstest(char *n, char *channel)
                 do_ddstest_one(j);
     }
 }
+#endif /* RTIO_DDS_COUNT */
 
 #if (defined CSR_SPIFLASH_BASE && defined CONFIG_SPIFLASH_PAGE_SIZE)
 static void fsread(char *key)
@@ -659,6 +662,7 @@ static void do_command(char *c)
     else if(strcmp(token, "ttloe") == 0) ttloe(get_token(&c), get_token(&c));
     else if(strcmp(token, "ttlo") == 0) ttlo(get_token(&c), get_token(&c));
 
+#if ((defined RTIO_DDS_COUNT) && (RTIO_DDS_COUNT > 0))
     else if(strcmp(token, "ddsbus") == 0) ddsbus(get_token(&c));
     else if(strcmp(token, "ddssel") == 0) ddssel(get_token(&c));
     else if(strcmp(token, "ddsw") == 0) ddsw(get_token(&c), get_token(&c));
@@ -668,6 +672,7 @@ static void do_command(char *c)
     else if(strcmp(token, "ddsfud") == 0) ddsfud();
     else if(strcmp(token, "ddsftw") == 0) ddsftw(get_token(&c), get_token(&c));
     else if(strcmp(token, "ddstest") == 0) ddstest(get_token(&c), get_token(&c));
+#endif
 
 #if (defined CSR_SPIFLASH_BASE && defined CONFIG_SPIFLASH_PAGE_SIZE)
     else if(strcmp(token, "fserase") == 0) fs_erase();