diff --git a/platform/mbed-trace/source/mbed_trace.c b/platform/mbed-trace/source/mbed_trace.c
index 4e1f16a..f085137 100644
--- a/platform/mbed-trace/source/mbed_trace.c
+++ b/platform/mbed-trace/source/mbed_trace.c
@@ -209,6 +209,7 @@
     m_trace.line_length = DEFAULT_TRACE_LINE_LENGTH;
     m_trace.tmp_data = 0;
     m_trace.tmp_data_length = DEFAULT_TRACE_TMP_LINE_LEN;
+    m_trace.tmp_data_ptr = 0;
     m_trace.prefix_f = 0;
     m_trace.suffix_f = 0;
     m_trace.printf  = mbed_trace_default_print;