diff --git a/gui/qt/main_window.py b/gui/qt/main_window.py
index dd213853..1b47b5a5 100644
--- a/gui/qt/main_window.py
+++ b/gui/qt/main_window.py
@@ -1904,15 +1904,25 @@ class ElectrumWindow(QMainWindow):
 
     def do_process_from_csvReader(self, csvReader):
         outputs = []
+        errors = []
+        errtext = ""
         try:
-            for row in csvReader:
+            for position, row in enumerate(csvReader):
                 address = row[0]
+                if not is_valid(address):
+                    errors.append((position, address))
+                    continue
                 amount = Decimal(row[1])
                 amount = int(100000000*amount)
                 outputs.append((address, amount))
         except (ValueError, IOError, os.error), reason:
             QMessageBox.critical(None, _("Unable to read file or no transaction found"), _("Electrum was unable to open your transaction file") + "\n" + str(reason))
             return
+        if errors != []:
+            for x in errors:
+                errtext += "CSV Row " + str(x[0]+1) + ": " + x[1] + "\n"
+            QMessageBox.critical(None, _("Invalid Addresses"), _("ABORTING! Invalid Addresses found:") + "\n\n" + errtext)
+            return
 
         try:
             tx = self.wallet.make_unsigned_transaction(outputs, None, None)
diff --git a/lib/wallet.py b/lib/wallet.py
index 7de861e9..a720f5ae 100644
--- a/lib/wallet.py
+++ b/lib/wallet.py
@@ -1262,7 +1262,7 @@ class NewWallet:
 
     def make_unsigned_transaction(self, outputs, fee=None, change_addr=None, domain=None ):
         for address, x in outputs:
-            assert is_valid(address)
+            assert is_valid(address), "Address " + address + " is invalid!"
         amount = sum( map(lambda x:x[1], outputs) )
         inputs, total, fee = self.choose_tx_inputs( amount, fee, domain )
         if not inputs: