diff --git a/lib/gd77.cc b/lib/gd77.cc
index 55ce5648..3a23ac2d 100644
--- a/lib/gd77.cc
+++ b/lib/gd77.cc
@@ -91,15 +91,14 @@ GD77::uploadCallsigns()
 
   size_t totb = _callsigns.memSize();
   unsigned bcount = 0;
-  // Then upload callsign DB
   for (int n=0; n<_callsigns.image(0).numElements(); n++) {
     unsigned addr = _callsigns.image(0).element(n).address();
     unsigned size = _callsigns.image(0).element(n).data().size();
     unsigned b0 = addr/BSIZE, nb = size/BSIZE;
-    RadioddityInterface::MemoryBank bank = (
-          (0x10000 > addr) ? RadioddityInterface::MEMBANK_CALLSIGN_LOWER : RadioddityInterface::MEMBANK_CALLSIGN_UPPER );
     for (unsigned b=0; b<nb; b++, bcount+=BSIZE) {
-      if (! _dev->write(bank, (b0+b)*BSIZE,
+      RadioddityInterface::MemoryBank bank = (
+            (0x10000 > (b0+b)*BSIZE) ? RadioddityInterface::MEMBANK_CALLSIGN_LOWER : RadioddityInterface::MEMBANK_CALLSIGN_UPPER );
+      if (! _dev->write(bank, ((b0+b)*BSIZE)&0xffff,
                         _callsigns.data((b0+b)*BSIZE, 0), BSIZE, _errorStack))
       {
         errMsg(_errorStack) << "Cannot write block " << (b0+b) << ".";
@@ -109,6 +108,7 @@ GD77::uploadCallsigns()
     }
   }
 
+
   _dev->write_finish();
   return true;
 }
diff --git a/lib/gd77_callsigndb.cc b/lib/gd77_callsigndb.cc
index e7522bf2..d8f4f3a1 100644
--- a/lib/gd77_callsigndb.cc
+++ b/lib/gd77_callsigndb.cc
@@ -7,6 +7,7 @@
 #define OFFSET_USERDB       0x00000
 
 #define USERDB_MAX_ENTRIES  10920
+#define USERDB_MAX_ENTRIES_PER_BANK 5460
 #define BLOCK_SIZE          32
 
 
@@ -103,14 +104,14 @@ GD77CallsignDB::encode(UserDatabase *calldb, const Selection &selection, const E
             [](const UserDatabase::User &a, const UserDatabase::User &b) { return a.id < b.id; });
 
   // Allocate segment for user db if requested
-  unsigned size = align_size(sizeof(userdb_t)+n*sizeof(userdb_entry_t), BLOCK_SIZE);
+  size_t size = align_size(sizeof(userdb_t)+n*sizeof(userdb_entry_t), BLOCK_SIZE);
   logDebug() << "Allocate 0x" << QString::number(size,16) << " bytes for call-sign DB.";
   this->image(0).addElement(OFFSET_USERDB, size);
 
   // Encode user DB
   userdb_t *userdb = (userdb_t *)this->data(OFFSET_USERDB);
   userdb->clear(); userdb->setSize(n);
-  userdb_entry_t *db = (userdb_entry_t *)this->data(OFFSET_USERDB+sizeof(userdb_t));
+  userdb_entry_t *db = (userdb_entry_t *)this->data(OFFSET_USERDB+sizeof(userdb_t), 0);
   for (unsigned i=0; i<n; i++) {
     db[i].fromEntry(users[i]);
   }