diff --git a/writer/HDF5DataFile.cpp b/writer/HDF5DataFile.cpp
index 79e03f706..1c47c12c8 100644
--- a/writer/HDF5DataFile.cpp
+++ b/writer/HDF5DataFile.cpp
@@ -45,7 +45,7 @@ declared_pixel_signed(msg.pixel_signed) {
     exptime.reserve(images_per_file);
     number.reserve(images_per_file);
 
-    uint64_t tmp_suffix;
+    uint64_t tmp_suffix = std::chrono::system_clock::now().time_since_epoch().count();
     try {
         if (!msg.arm_date.empty())
             tmp_suffix = parse_UTC_to_ms(msg.arm_date);
diff --git a/writer/HDF5NXmx.cpp b/writer/HDF5NXmx.cpp
index c37e745b0..30eb8d1b8 100644
--- a/writer/HDF5NXmx.cpp
+++ b/writer/HDF5NXmx.cpp
@@ -23,7 +23,7 @@ std::string HDF5Metadata::MasterFileName(const StartMessage &start) {
 NXmx::NXmx(const StartMessage &start)
         : start_message(start),
           filename(HDF5Metadata::MasterFileName(start)) {
-    uint64_t tmp_suffix;
+    uint64_t tmp_suffix = std::chrono::system_clock::now().time_since_epoch().count();
     try {
         if (!start.arm_date.empty())
             tmp_suffix = parse_UTC_to_ms(start.arm_date);