diff --git a/libraries/AP_InertialSensor/BatchSampler.cpp b/libraries/AP_InertialSensor/BatchSampler.cpp
index 0da3f31bb5..6f0eed83eb 100644
--- a/libraries/AP_InertialSensor/BatchSampler.cpp
+++ b/libraries/AP_InertialSensor/BatchSampler.cpp
@@ -56,7 +56,7 @@ void AP_InertialSensor::BatchSampler::init()
     _required_count -= _required_count % 32; // round down to nearest multiple of 32
 
     const uint32_t total_allocation = 3*_required_count*sizeof(uint16_t);
-    gcs().send_text(MAV_SEVERITY_DEBUG, "INS: alloc %u bytes for ISB (free=%u)", total_allocation, hal.util->available_memory());
+    gcs().send_text(MAV_SEVERITY_DEBUG, "INS: alloc %u bytes for ISB (free=%u)", (unsigned int)total_allocation, (unsigned int)hal.util->available_memory());
 
     data_x = (int16_t*)calloc(_required_count, sizeof(int16_t));
     data_y = (int16_t*)calloc(_required_count, sizeof(int16_t));
@@ -68,7 +68,7 @@ void AP_InertialSensor::BatchSampler::init()
         data_x = nullptr;
         data_y = nullptr;
         data_z = nullptr;
-        gcs().send_text(MAV_SEVERITY_WARNING, "Failed to allocate %u bytes for IMU batch sampling", total_allocation);
+        gcs().send_text(MAV_SEVERITY_WARNING, "Failed to allocate %u bytes for IMU batch sampling", (unsigned int)total_allocation);
         return;
     }