diff --git a/helper/build_config b/helper/build_config
index 10628bbe..b3e83d9a 100755
--- a/helper/build_config
+++ b/helper/build_config
@@ -76,9 +76,16 @@ umask 0077
 
 TT_WRAPPER="${HELPER}/tt2-wrapper"
 
+# generate in a temporary location, then move if successful
+tt_tmp_output_file_base="$(basename "${output_file}")"
+tt_tmp_output_file="$(mktemp ngcpcfg."${tt_tmp_output_file_base}".XXXXXXXXXX)"
+
 log_debug "Output file ${output_file} based on ${input_file}"
-log_debug "Executing: $TT_WRAPPER ${input_file} > ${output_file}"
-if "$TT_WRAPPER" "${input_file}" > "${output_file}" 2>/dev/null ; then
+log_debug "Executing: $TT_WRAPPER ${input_file} > ${tt_tmp_output_file}"
+log_debug "      and: cat ${tt_tmp_output_file} > ${output_file}"
+if "$TT_WRAPPER" "${input_file}" > "${tt_tmp_output_file}" 2>/dev/null &&
+   cat "${tt_tmp_output_file}" > "${output_file}" 2>/dev/null ; then
+  rm -f "${tt_tmp_output_file}"
   log_info "Generating ${output_file}: OK"
   RC=0
 else
@@ -89,8 +96,9 @@ else
   for f in "${input_file}" ${host_conf:-} ${local_conf:-} "$NGCPCTL_CONFIG" "${NETWORK_CONFIG:-}" ${EXTRA_CONFIG_FILES:-} "$CONSTANTS_CONFIG" ; do
     [ -r "$f" ] && log_info "$f"
   done
-  log_info "Running /usr/share/ngcp-ngcpcfg/helper/tt2-wrapper <file> should provide more details."
-
+  log_info "Running /usr/share/ngcp-ngcpcfg/helper/tt2-wrapper <file>"
+  log_info "or inspecting temporary ${tt_tmp_output_file}"
+  log_info "should provide more details."
 fi
 
 if [ -L "$output_file" ] ; then