diff --git a/cpp/base.hpp b/cpp/base.hpp
index 4bbaa48631249914058d3b8bc869684b24600924..07667151d1023d08bd3e884ca9030bd68150d20d 100644
--- a/cpp/base.hpp
+++ b/cpp/base.hpp
@@ -148,8 +148,8 @@ inline void DEBUG_MSG(const char * format, ...)
             "MPIrank%.4d ",
             myrank);
     vsnprintf(
-            debug_message_buffer + 8,
-            message_buffer_length - 8,
+            debug_message_buffer + 12,
+            message_buffer_length - 12,
             format,
             argptr);
     va_end(argptr);
@@ -165,8 +165,8 @@ inline void DEBUG_MSG_WAIT(MPI_Comm communicator, const char * format, ...)
             "MPIrank%.4d ",
             myrank);
     vsnprintf(
-            debug_message_buffer + 8,
-            message_buffer_length - 8,
+            debug_message_buffer + 12,
+            message_buffer_length - 12,
             format,
             argptr);
     va_end(argptr);