diff --git a/lldb/source/Core/Communication.cpp b/lldb/source/Core/Communication.cpp
--- a/lldb/source/Core/Communication.cpp
+++ b/lldb/source/Core/Communication.cpp
@@ -176,8 +176,8 @@
 
   std::lock_guard<std::mutex> guard(m_write_mutex);
   LLDB_LOG(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_COMMUNICATION),
-           "{0} Communication::Write (src = {1}, src_len = %" PRIu64
-           ") connection = {2}",
+           "{0} Communication::Write (src = {1}, src_len = {2}"
+           ") connection = {3}",
            this, src, (uint64_t)src_len, connection_sp.get());
 
   if (connection_sp)