diff --git a/mission/tmtc/PersistentTmStore.cpp b/mission/tmtc/PersistentTmStore.cpp
index c6f59007..91a8be48 100644
--- a/mission/tmtc/PersistentTmStore.cpp
+++ b/mission/tmtc/PersistentTmStore.cpp
@@ -28,6 +28,42 @@ PersistentTmStore::PersistentTmStore(object_id_t objectId, const char* baseDir,
   calcDiffSeconds(intervalUnit, intervalCount);
 }
 
+ReturnValue_t PersistentTmStore::assignAndOrCreateMostRecentFile() {
+  using namespace std::filesystem;
+  for (auto const& file : directory_iterator(basePath)) {
+    if (file.is_directory()) {
+      continue;
+    }
+    auto pathStr = file.path().string();
+    if (pathStr.find(baseName) == std::string::npos) {
+      continue;
+    }
+    unsigned int underscorePos = pathStr.find_last_of('_');
+    std::string stampStr = pathStr.substr(underscorePos + 1);
+    struct tm time {};
+    if (nullptr == strptime(stampStr.c_str(), FILE_DATE_FORMAT, &time)) {
+      sif::error << "PersistentTmStore::assignOrCreateMostRecentFile: Error reading timestamp"
+                 << std::endl;
+      // Delete the file and re-create it.
+      activeFile = std::nullopt;
+      std::filesystem::remove(file.path());
+      break;
+    }
+    time_t fileEpoch = timegm(&time);
+    // There is still a file within the active time window, so re-use that file for new TMs to
+    // store.
+    if (fileEpoch + rolloverDiffSeconds > currentTv.tv_sec) {
+      activeFileTv.tv_sec = fileEpoch;
+      activeFile = file.path();
+      break;
+    }
+  }
+  if (not activeFile.has_value()) {
+    return createMostRecentFile();
+  }
+  return returnvalue::OK;
+}
+
 ReturnValue_t PersistentTmStore::handleCommandQueue(StorageManagerIF& ipcStore,
                                                     TmFunnelBase& tmFunnel) {
   CommandMessage cmdMessage;
@@ -51,14 +87,16 @@ ReturnValue_t PersistentTmStore::handleCommandQueue(StorageManagerIF& ipcStore,
     } else if (cmd == TmStoreMessage::DOWNLINK_STORE_CONTENT_TIME) {
       store_address_t storeId = TmStoreMessage::getStoreId(&cmdMessage);
       auto accessor = ipcStore.getData(storeId);
+      if (accessor.second.size() < 8) {
+        return returnvalue::FAILED;
+      }
       uint32_t dumpFromUnixSeconds;
       uint32_t dumpUntilUnixSeconds;
-      size_t size = accessor.second.size();
+      size_t size = 8;
       SerializeAdapter::deSerialize(&dumpFromUnixSeconds, accessor.second.data(), &size,
                                     SerializeIF::Endianness::NETWORK);
-      SerializeAdapter::deSerialize(&dumpUntilUnixSeconds, accessor.second.data(), &size,
+      SerializeAdapter::deSerialize(&dumpUntilUnixSeconds, accessor.second.data() + 4, &size,
                                     SerializeIF::Endianness::NETWORK);
-      // TODO: TM store missing, and maybe there is a better way to do this?
       dumpFromUpTo(dumpFromUnixSeconds, dumpUntilUnixSeconds, tmFunnel);
     }
   }
@@ -110,30 +148,32 @@ ReturnValue_t PersistentTmStore::storePacket(PusTmReader& reader) {
     updateBaseDir();
   }
   // It is assumed here that the filesystem is usable.
-  if (not mostRecentFile) {
-    assignAndOrCreateMostRecentFile();
+  if (not activeFile.has_value()) {
+    ReturnValue_t result = assignAndOrCreateMostRecentFile();
+    if (result != returnvalue::OK) {
+      return result;
+    }
   }
 
-  if (currentTv.tv_sec < mostRecentTv.value().tv_sec or
-      currentTv.tv_sec - mostRecentTv.value().tv_sec > static_cast<int>(rolloverDiffSeconds)) {
-    if (file_size(mostRecentFile.value()) + reader.getFullPacketLen() > fileBuf.size()) {
+  if (currentTv.tv_sec < activeFileTv.tv_sec or
+      currentTv.tv_sec - activeFileTv.tv_sec > static_cast<int>(rolloverDiffSeconds)) {
+    if (file_size(activeFile.value()) + reader.getFullPacketLen() > fileBuf.size()) {
       uint8_t appendedCounter = 1;
       path rolloverName;
       while (true) {
-        rolloverName =
-            path(mostRecentFile.value().string() + "." + std::to_string(appendedCounter));
+        rolloverName = path(activeFile.value().string() + "." + std::to_string(appendedCounter));
         if (not exists(rolloverName)) {
           break;
         }
         appendedCounter++;
       }
-      rename(mostRecentFile.value(), rolloverName);
-      std::ofstream of(mostRecentFile.value(), std::ios::binary);
+      rename(activeFile.value(), rolloverName);
+      std::ofstream of(activeFile.value(), std::ios::binary);
     }
   }
 
   // Rollover conditions were handled, write to file now
-  std::ofstream of(mostRecentFile.value(), std::ios::app | std::ios::binary);
+  std::ofstream of(activeFile.value(), std::ios::app | std::ios::binary);
   of.write(reinterpret_cast<const char*>(reader.getFullData()),
            static_cast<std::streamsize>(reader.getFullPacketLen()));
   return returnvalue::OK;
@@ -161,51 +201,6 @@ void PersistentTmStore::updateBaseDir() {
   baseDirUninitialized = false;
 }
 
-void PersistentTmStore::assignAndOrCreateMostRecentFile() {
-  using namespace std::filesystem;
-  for (auto const& file : directory_iterator(basePath)) {
-    if (file.is_directory()) {
-      continue;
-    }
-    auto pathStr = file.path().string();
-    Clock::TimeOfDay_t tod;
-    if (pathStr.find(baseName) == std::string::npos) {
-      continue;
-    }
-    unsigned int underscorePos = pathStr.find_last_of('_');
-    std::string stampStr = pathStr.substr(underscorePos + 1);
-    int count = sscanf(stampStr.c_str(),
-                       "%04" SCNu32 "-%02" SCNu32 "-%02" SCNu32 "T%02" SCNu32 "-%02" SCNu32
-                       "-%02" SCNu32 "Z",
-                       &tod.year, &tod.month, &tod.day, &tod.hour, &tod.minute, &tod.second);
-    if (count != 6) {
-      continue;
-    }
-    timeval tv{};
-    Clock::convertTimeOfDayToTimeval(&tod, &tv);
-    if (not mostRecentTv || tv > mostRecentTv.value()) {
-      mostRecentTv = tv;
-      mostRecentFile = file.path();
-    }
-  }
-  if (not mostRecentFile) {
-    unsigned currentIdx = 0;
-    path pathStart = basePath / baseName;
-    memcpy(fileBuf.data() + currentIdx, pathStart.c_str(), pathStart.string().length());
-    currentIdx += pathStart.string().length();
-    Clock::TimeOfDay_t tod;
-    Clock::convertTimevalToTimeOfDay(&currentTv, &tod);
-    currentIdx += sprintf(reinterpret_cast<char*>(fileBuf.data() + currentIdx),
-                          "_%04" PRIu32 "-%02" PRIu32 "-%02" PRIu32 "T%02" PRIu32 "-%02" PRIu32
-                          "-%02" PRIu32 "Z.bin",
-                          tod.year, tod.month, tod.day, tod.hour, tod.minute, tod.second);
-    path newPath(std::string(reinterpret_cast<const char*>(fileBuf.data()), currentIdx));
-    std::ofstream of(newPath, std::ios::binary);
-    mostRecentFile = newPath;
-    mostRecentTv = currentTv;
-  }
-}
-
 void PersistentTmStore::addApid(uint16_t apid) {
   if (not filter.apid) {
     filter.apid = std::vector<uint16_t>({apid});
@@ -234,19 +229,17 @@ void PersistentTmStore::addServiceSubservice(uint8_t service, uint8_t subservice
 void PersistentTmStore::deleteUpTo(uint32_t unixSeconds) {
   using namespace std::filesystem;
   for (auto const& file : directory_iterator(basePath)) {
-    if (file.is_directory() or
-        (mostRecentFile.has_value() and (mostRecentFile.value() == file.path()))) {
+    if (file.is_directory() or (activeFile.has_value() and (activeFile.value() == file.path()))) {
       continue;
     }
-    Clock::TimeOfDay_t tod;
-    pathToTod(file.path(), tod);
-    timeval time{};
-    ReturnValue_t result = Clock::convertTimeOfDayToTimeval(&tod, &time);
-    if (result != returnvalue::OK) {
-      sif::error << "TOD to time conversion failed for file " << file << std::endl;
+    // Convert file time to the UNIX epoch
+    struct tm fileTime {};
+    if (pathToTm(file.path(), fileTime) != returnvalue::OK) {
+      sif::error << "Time extraction for " << file << "failed" << std::endl;
       continue;
     }
-    if (time.tv_sec + rolloverDiffSeconds < unixSeconds) {
+    time_t epoch = timegm(&fileTime);
+    if (epoch + rolloverDiffSeconds < unixSeconds) {
       std::filesystem::remove(file.path());
     }
   }
@@ -259,33 +252,26 @@ void PersistentTmStore::dumpFromUpTo(uint32_t fromUnixSeconds, uint32_t upToUnix
     if (file.is_directory()) {
       continue;
     }
-    if (mostRecentFile.has_value() and mostRecentTv.has_value() and
-        (file.path() == mostRecentFile.value()) and
-        (upToUnixSeconds < static_cast<uint32_t>(mostRecentTv.value().tv_sec))) {
+    struct tm fileTime {};
+    if (pathToTm(file.path(), fileTime) != returnvalue::OK) {
+      sif::error << "Time extraction for file " << file << "failed" << std::endl;
       continue;
     }
-    Clock::TimeOfDay_t tod;
-    pathToTod(file.path(), tod);
-    timeval time{};
-    ReturnValue_t result = Clock::convertTimeOfDayToTimeval(&tod, &time);
-    if (result != returnvalue::OK) {
-      sif::error << "TOD to time conversion failed for file " << file << std::endl;
-      continue;
-    }
-    auto timeUnsigned = static_cast<uint32_t>(time.tv_sec);
-    if (timeUnsigned > fromUnixSeconds && timeUnsigned + rolloverDiffSeconds < upToUnixSeconds) {
-      fileToPackets(file, timeUnsigned, funnel);
+    auto fileEpoch = static_cast<uint32_t>(timegm(&fileTime));
+    if ((fileEpoch > fromUnixSeconds) and (fileEpoch + rolloverDiffSeconds <= upToUnixSeconds)) {
+      fileToPackets(file, fileEpoch, funnel);
     }
   }
 }
 
-void PersistentTmStore::pathToTod(const std::filesystem::path& path, Clock::TimeOfDay_t& tod) {
+ReturnValue_t PersistentTmStore::pathToTm(const std::filesystem::path& path, struct tm& time) {
   auto pathStr = path.string();
   size_t splitChar = pathStr.find('_');
-  auto timeOnlyStr = pathStr.substr(splitChar);
-  sscanf(timeOnlyStr.data(),
-         "%04" SCNu32 "-%02" SCNu32 "-%02" SCNu32 "T%02" SCNu32 "-%02" SCNu32 "-%02" SCNu32 "Z",
-         &tod.year, &tod.month, &tod.day, &tod.hour, &tod.minute, &tod.second);
+  auto timeOnlyStr = pathStr.substr(splitChar + 1);
+  if (nullptr == strptime(timeOnlyStr.c_str(), FILE_DATE_FORMAT, &time)) {
+    return returnvalue::FAILED;
+  }
+  return returnvalue::OK;
 }
 
 void PersistentTmStore::fileToPackets(const std::filesystem::path& path, uint32_t unixStamp,
@@ -320,3 +306,37 @@ void PersistentTmStore::fileToPackets(const std::filesystem::path& path, uint32_
     }
   }
 }
+
+ReturnValue_t PersistentTmStore::createMostRecentFile() {
+  using namespace std::filesystem;
+  unsigned currentIdx = 0;
+  path pathStart = basePath / baseName;
+  memcpy(fileBuf.data() + currentIdx, pathStart.c_str(), pathStart.string().length());
+  currentIdx += pathStart.string().length();
+  fileBuf[currentIdx] = '_';
+  currentIdx += 1;
+  time_t epoch = currentTv.tv_sec;
+  struct tm* time = gmtime(&epoch);
+  size_t writtenBytes = strftime(reinterpret_cast<char*>(fileBuf.data() + currentIdx),
+                                 fileBuf.size(), FILE_DATE_FORMAT, time);
+  if (writtenBytes == 0) {
+    sif::error << "PersistentTmStore::createMostRecentFile: Could not create file timestamp"
+               << std::endl;
+    return returnvalue::FAILED;
+  }
+  currentIdx += writtenBytes;
+  strncpy(reinterpret_cast<char*>(fileBuf.data() + currentIdx), ".bin",
+          fileBuf.size() - currentIdx);
+  currentIdx += 4;
+
+  path newPath(std::string(reinterpret_cast<const char*>(fileBuf.data()), currentIdx));
+  std::ofstream of(newPath, std::ios::binary);
+  activeFile = newPath;
+  activeFileTv = currentTv;
+  return returnvalue::OK;
+}
+
+ReturnValue_t PersistentTmStore::initializeTmStore() {
+  updateBaseDir();
+  return assignAndOrCreateMostRecentFile();
+}
diff --git a/mission/tmtc/PersistentTmStore.h b/mission/tmtc/PersistentTmStore.h
index 4285d146..bcd83a71 100644
--- a/mission/tmtc/PersistentTmStore.h
+++ b/mission/tmtc/PersistentTmStore.h
@@ -34,6 +34,7 @@ class PersistentTmStore : public TmStoreFrontendSimpleIF, public SystemObject {
                     RolloverInterval intervalUnit, uint32_t intervalCount, timeval& currentTv,
                     StorageManagerIF& tmStore, SdCardMountedIF& sdcMan);
 
+  ReturnValue_t initializeTmStore();
   ReturnValue_t handleCommandQueue(StorageManagerIF& ipcStore, TmFunnelBase& tmFunnel);
 
   void addApid(uint16_t apid);
@@ -44,11 +45,12 @@ class PersistentTmStore : public TmStoreFrontendSimpleIF, public SystemObject {
   void dumpFrom(uint32_t fromUnixSeconds, TmFunnelBase& tmFunnel);
   void dumpFromUpTo(uint32_t fromUnixSeconds, uint32_t upToUnixSeconds, TmFunnelBase& tmFunnel);
 
-  void updateBaseDir();
   ReturnValue_t passPacket(PusTmReader& reader);
 
  private:
   static constexpr size_t MAX_FILESIZE = 8192;
+  // ISO8601 timestamp.
+  static constexpr char FILE_DATE_FORMAT[] = "%FT%H%M%SZ";
 
   MessageQueueIF* tcQueue;
   PacketFilter filter;
@@ -60,8 +62,8 @@ class PersistentTmStore : public TmStoreFrontendSimpleIF, public SystemObject {
   uint32_t rolloverDiffSeconds = 0;
   std::array<uint8_t, MAX_FILESIZE> fileBuf{};
   timeval& currentTv;
-  std::optional<timeval> mostRecentTv;
-  std::optional<std::filesystem::path> mostRecentFile;
+  timeval activeFileTv{};
+  std::optional<std::filesystem::path> activeFile;
   SdCardMountedIF& sdcMan;
   StorageManagerIF& tmStore;
 
@@ -72,9 +74,11 @@ class PersistentTmStore : public TmStoreFrontendSimpleIF, public SystemObject {
   [[nodiscard]] MessageQueueId_t getCommandQueue() const override;
 
   void calcDiffSeconds(RolloverInterval intervalUnit, uint32_t intervalCount);
-  void assignAndOrCreateMostRecentFile();
-  static void pathToTod(const std::filesystem::path& path, Clock::TimeOfDay_t& tod);
+  ReturnValue_t createMostRecentFile();
+  static ReturnValue_t pathToTm(const std::filesystem::path& path, struct tm& time);
   void fileToPackets(const std::filesystem::path& path, uint32_t unixStamp, TmFunnelBase& funnel);
+  void updateBaseDir();
+  ReturnValue_t assignAndOrCreateMostRecentFile();
   ReturnValue_t storePacket(PusTmReader& reader);
 };
 
diff --git a/mission/tmtc/PusTmFunnel.cpp b/mission/tmtc/PusTmFunnel.cpp
index 2b61e19a..db645042 100644
--- a/mission/tmtc/PusTmFunnel.cpp
+++ b/mission/tmtc/PusTmFunnel.cpp
@@ -29,9 +29,9 @@ PusTmFunnel::PusTmFunnel(TmFunnelBase::FunnelCfg cfg, TimeReaderIF &timeReader,
   miscStore.addService(17);
   miscStore.addService(2);
   miscStore.addService(200);
+  miscStore.addService(201);
   okStore.addApid(config::EIVE_PUS_APID);
   okStore.addServiceSubservice(5, 1);
-  okStore.addApid(config::EIVE_PUS_APID);
   okStore.addService(8);
   okStore.addServiceSubservice(1, 1);
   okStore.addServiceSubservice(1, 3);
@@ -51,21 +51,27 @@ PusTmFunnel::~PusTmFunnel() = default;
 
 ReturnValue_t PusTmFunnel::performOperation(uint8_t) {
   CommandMessage cmdMessage;
-  ReturnValue_t result = okStore.handleCommandQueue(ipcStore, *this);
-  if (result != returnvalue::OK) {
-    sif::error << "PusTmFunnel::performOperation: Issue handling OK store command" << std::endl;
-  }
-  result = notOkStore.handleCommandQueue(ipcStore, *this);
-  if (result != returnvalue::OK) {
-    sif::error << "PusTmFunnel::performOperation: Issue handling NOT OK store command" << std::endl;
-  }
-  result = hkStore.handleCommandQueue(ipcStore, *this);
-  if (result != returnvalue::OK) {
-    sif::error << "PusTmFunnel::performOperation: Issue handling HK store command" << std::endl;
-  }
-  result = miscStore.handleCommandQueue(ipcStore, *this);
-  if (result != returnvalue::OK) {
-    sif::error << "PusTmFunnel::performOperation: Issue handling MISC store command" << std::endl;
+  ReturnValue_t result;
+  try {
+    result = okStore.handleCommandQueue(ipcStore, *this);
+    if (result != returnvalue::OK) {
+      sif::error << "PusTmFunnel::performOperation: Issue handling OK store command" << std::endl;
+    }
+    result = notOkStore.handleCommandQueue(ipcStore, *this);
+    if (result != returnvalue::OK) {
+      sif::error << "PusTmFunnel::performOperation: Issue handling NOT OK store command"
+                 << std::endl;
+    }
+    result = hkStore.handleCommandQueue(ipcStore, *this);
+    if (result != returnvalue::OK) {
+      sif::error << "PusTmFunnel::performOperation: Issue handling HK store command" << std::endl;
+    }
+    result = miscStore.handleCommandQueue(ipcStore, *this);
+    if (result != returnvalue::OK) {
+      sif::error << "PusTmFunnel::performOperation: Issue handling MISC store command" << std::endl;
+    }
+  } catch (const std::bad_optional_access &e) {
+    sif::error << e.what() << "when handling TM store command" << std::endl;
   }
 
   TmTcMessage currentMessage;
@@ -134,10 +140,10 @@ const char *PusTmFunnel::getName() const { return "PUS TM Funnel"; }
 
 void PusTmFunnel::initStoresIfPossible(bool sdCardUsable) {
   if (not storesInitialized and sdCardUsable) {
-    miscStore.updateBaseDir();
-    okStore.updateBaseDir();
-    hkStore.updateBaseDir();
-    notOkStore.updateBaseDir();
+    miscStore.initializeTmStore();
+    okStore.initializeTmStore();
+    hkStore.initializeTmStore();
+    notOkStore.initializeTmStore();
     storesInitialized = true;
   }
 }
diff --git a/mission/tmtc/Service15TmStorage.cpp b/mission/tmtc/Service15TmStorage.cpp
index 9864b566..d61d587d 100644
--- a/mission/tmtc/Service15TmStorage.cpp
+++ b/mission/tmtc/Service15TmStorage.cpp
@@ -46,27 +46,33 @@ ReturnValue_t Service15TmStorage::prepareCommand(CommandMessage *message, uint8_
                                                  const uint8_t *tcData, size_t tcDataLen,
                                                  uint32_t *state, object_id_t objectId) {
   if (subservice == Subservices::START_BY_TIME_RANGE_RETRIEVAL) {
+    // TODO: Hardcoded to UNIX timestamps.. Should allow arbitrary timestamp and let receiver
+    //       to time reading and reply handling
     if (tcDataLen != 12) {
       return INVALID_TC;
     }
     store_address_t storeId;
-    ReturnValue_t result = ipcStore->addData(&storeId, tcData, tcDataLen);
+    ReturnValue_t result = ipcStore->addData(&storeId, tcData + 4, tcDataLen - 4);
     if (result != OK) {
       return result;
     }
     // Store timestamps
     TmStoreMessage::setDownlinkContentTimeMessage(message, storeId);
+    return CommandingServiceBase::EXECUTION_COMPLETE;
   } else if (subservice == Subservices::DELETE_UP_TO) {
+    // TODO: Hardcoded to UNIX timestamps.. Should allow arbitrary timestamp and let receiver
+    //       to time reading and reply handling
     if (tcDataLen != 8) {
       return INVALID_TC;
     }
     store_address_t storeId;
-    ReturnValue_t result = ipcStore->addData(&storeId, tcData, tcDataLen);
+    ReturnValue_t result = ipcStore->addData(&storeId, tcData + 4, tcDataLen - 4);
     if (result != OK) {
       return result;
     }
     // Store timestamps
     TmStoreMessage::setDeleteContentTimeMessage(message, storeId);
+    return CommandingServiceBase::EXECUTION_COMPLETE;
   }
   return OK;
 }
diff --git a/tmtc b/tmtc
index 4917ddbb..fb676dc9 160000
--- a/tmtc
+++ b/tmtc
@@ -1 +1 @@
-Subproject commit 4917ddbbe4abd03ca7c7bb4ca5c80970e9b3b6bf
+Subproject commit fb676dc90fe77585959297c36c828a7e852637c8