diff --git a/libraries/AP_RCProtocol/AP_RCProtocol_DSM.cpp b/libraries/AP_RCProtocol/AP_RCProtocol_DSM.cpp
index bda3451190..1120b6b862 100644
--- a/libraries/AP_RCProtocol/AP_RCProtocol_DSM.cpp
+++ b/libraries/AP_RCProtocol/AP_RCProtocol_DSM.cpp
@@ -169,7 +169,7 @@ void AP_RCProtocol_DSM::dsm_guess_format(bool reset, const uint8_t dsm_frame[16]
     }
 
     /* call ourselves to reset our state ... we have to try again */
-    debug("DSM: format detect fail, 10: 0x%08x %d 11: 0x%08x %d", cs10, votes10, cs11, votes11);
+    debug("DSM: format detect fail, 10: 0x%08x %u 11: 0x%08x %u", cs10, votes10, cs11, votes11);
     dsm_guess_format(true, dsm_frame);
 }
 
diff --git a/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.cpp b/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.cpp
index 76d2387548..432340965b 100644
--- a/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.cpp
+++ b/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.cpp
@@ -296,7 +296,7 @@ void AP_RCProtocol_SUMD::_process_byte(uint32_t timestamp_us, uint8_t byte)
 
             for (i = 4; i < _rxpacket.length; i++) {
 #ifdef SUMD_DEBUG
-                hal.console->printf("ch[%d] : %x %x [ %x    %d ]\n", i + 1, _rxpacket.sumd_data[i * 2 + 1], _rxpacket.sumd_data[i * 2 + 2],
+                hal.console->printf("ch[%u] : %x %x [ %x    %d ]\n", i + 1, _rxpacket.sumd_data[i * 2 + 1], _rxpacket.sumd_data[i * 2 + 2],
                                     ((_rxpacket.sumd_data[i * 2 + 1] << 8) | _rxpacket.sumd_data[i * 2 + 2]) >> 3,
                                     ((_rxpacket.sumd_data[i * 2 + 1] << 8) | _rxpacket.sumd_data[i * 2 + 2]) >> 3);
 #endif