diff --git a/Tools/Replay/LR_MsgHandler.cpp b/Tools/Replay/LR_MsgHandler.cpp
index 9f9bdc0f50..e5b0a49809 100644
--- a/Tools/Replay/LR_MsgHandler.cpp
+++ b/Tools/Replay/LR_MsgHandler.cpp
@@ -2,6 +2,8 @@
 #include "LogReader.h"
 #include "Replay.h"
 
+#include <cinttypes>
+
 extern const AP_HAL::HAL& hal;
 
 LR_MsgHandler::LR_MsgHandler(struct log_Format &_f,
@@ -427,7 +429,7 @@ void LR_MsgHandler_PM::process_message(uint8_t *msg)
     uint32_t new_logdrop;
     if (field_value(msg, "LogDrop", new_logdrop) &&
         new_logdrop != 0) {
-        printf("PM.LogDrop: %u dropped at timestamp %lu\n", new_logdrop, last_timestamp_usec);
+        printf("PM.LogDrop: %u dropped at timestamp %" PRIu64 "\n", new_logdrop, last_timestamp_usec);
     }
 }
 
diff --git a/Tools/Replay/Replay.cpp b/Tools/Replay/Replay.cpp
index 5b767df323..a9b924d698 100644
--- a/Tools/Replay/Replay.cpp
+++ b/Tools/Replay/Replay.cpp
@@ -803,12 +803,12 @@ void Replay::show_packet_counts()
     for(uint16_t i=0;i<LOGREADER_MAX_FORMATS;i++) {
         if (counts[i] != 0) {
             logreader.format_type(i, format_type);
-            printf("%10ld %s\n", counts[i], format_type);
+            printf("%10" PRIu64 " %s\n", counts[i], format_type);
             total += counts[i];
         }
     }
 
-    printf("%ld total\n", total);
+    printf("%" PRIu64 " total\n", total);
 }
 
 void Replay::loop()
@@ -830,7 +830,7 @@ void Replay::loop()
     if (last_timestamp != 0) {
         uint64_t gap = AP_HAL::micros64() - last_timestamp;
         if (gap > 40000) {
-            ::printf("Gap in log at timestamp=%lu of length %luus\n",
+            ::printf("Gap in log at timestamp=%" PRIu64 " of length %" PRIu64 "us\n",
                      last_timestamp, gap);
         }
     }