diff --git a/block.py b/block.py
index 7d147f4..79d0aee 100644
--- a/block.py
+++ b/block.py
@@ -9,6 +9,7 @@ import asyncio
 # from decimal import Decimal
 
 import view
+from util import isoformatseconds
 
 
 class BlockStore(object):
@@ -156,7 +157,7 @@ class BlockView(view.View):
         self._pad.addstr(0, 46, "[J/K: browse, HOME/END: quicker, L: best, TAB: manual]", CYELLOW)
 
         self._pad.addstr(0, 1, "Time {}".format(
-            datetime.datetime.utcfromtimestamp(block["time"]).isoformat(timespec="seconds")
+            isoformatseconds(datetime.datetime.utcfromtimestamp(block["time"]))
         ), CBOLD)
         self._pad.addstr(0, 31, "Height {}".format(block["height"]), CBOLD)
 
diff --git a/footer.py b/footer.py
index 6930714..71aa727 100644
--- a/footer.py
+++ b/footer.py
@@ -5,6 +5,7 @@
 import curses
 
 from macros import MODES, MIN_WINDOW_SIZE
+from util import isoformatseconds
 
 
 class FooterView(object):
@@ -41,7 +42,7 @@ class FooterView(object):
             x += len(mode_string) + 5
 
         if self._dt:
-            self._pad.addstr(0, 81, self._dt.isoformat(timespec="seconds")[:19], CYELLOW + CBOLD)
+            self._pad.addstr(0, 81, isoformatseconds(self._dt)[:19], CYELLOW + CBOLD)
 
         await self._draw_pad_to_screen()
 
diff --git a/transaction.py b/transaction.py
index 8ac6514..1b8b7a8 100644
--- a/transaction.py
+++ b/transaction.py
@@ -8,6 +8,7 @@ import asyncio
 
 import view
 from macros import TX_VERBOSE_MODE
+from util import isoformatseconds
 
 
 class TransactionStore(object):
@@ -69,7 +70,7 @@ class TransactionView(view.View):
         CBOLD = curses.A_BOLD
 
         self._pad.addstr(0, 1, "time {}".format(
-            datetime.datetime.utcfromtimestamp(transaction["time"]).isoformat(timespec="seconds")
+            isoformatseconds(datetime.datetime.utcfromtimestamp(transaction["time"]))
         ), CBOLD)
         self._pad.addstr(1, 1, "size {}b".format(transaction["size"]), CBOLD)
         self._pad.addstr(1, 15, "vsize {}b".format(transaction["vsize"]), CBOLD)
diff --git a/util.py b/util.py
new file mode 100644
index 0000000..b77abb7
--- /dev/null
+++ b/util.py
@@ -0,0 +1,7 @@
+def isoformatseconds(dt):
+    try:
+        return dt.isoformat(timespec="seconds")
+    except TypeError:
+        # Python 3.5 and below
+        # 'timespec' is an invalid keyword argument for this function
+        return dt.isoformat().split(".")[0]
diff --git a/wallet.py b/wallet.py
index 8528adb..73221f2 100644
--- a/wallet.py
+++ b/wallet.py
@@ -7,6 +7,7 @@ import curses
 import asyncio
 
 import view
+from util import isoformatseconds
 
 class WalletView(view.View):
     _mode_name = "wallet"
@@ -56,7 +57,7 @@ class WalletView(view.View):
                     self._pad.addstr(2+((i-offset)*3)+1, 1, " " * 98, color)
 
                 self._pad.addstr(2+((i-offset)*3), 1, "{}".format(
-                    datetime.datetime.utcfromtimestamp(tx["timereceived"]).isoformat(timespec="seconds")
+                    isoformatseconds(datetime.datetime.utcfromtimestamp(tx["timereceived"]))
                 ), color)
                 self._pad.addstr(2+((i-offset)*3), 30, "block: {: 7d}".format(tx["blockindex"]), color)
                 self._pad.addstr(2+((i-offset)*3), 81, "{: 15.8f} BTC".format(