diff --git a/silkaj/money.py b/silkaj/money.py
index b23f9ad3354bf51250894758d6048c9d7b51ed0c..d030a661dd342240acebf0228125296e8e0f577c 100644
--- a/silkaj/money.py
+++ b/silkaj/money.py
@@ -138,7 +138,7 @@ def get_sources(pubkey):
     listinput = list()
     amount = 0
     for source in sources["sources"]:
-        if source["conditions"] == "SIG(" + pubkey + ")":
+        if source["conditions"] == f"SIG({pubkey})":
             listinput.append(
                 InputSource(
                     amount=source["amount"],
@@ -161,7 +161,7 @@ def get_sources(pubkey):
         identifier = pending["hash"]
         for i, output in enumerate(pending["outputs"]):
             outputsplited = output.split(":")
-            if outputsplited[2] == "SIG(" + pubkey + ")":
+            if outputsplited[2] == f"SIG({pubkey})":
                 inputgenerated = InputSource(
                     amount=int(outputsplited[0]),
                     base=int(outputsplited[1]),
diff --git a/silkaj/tui.py b/silkaj/tui.py
index 985c97455fb79ab97714099e7ce8e02e8fa06b6b..eaecea329cf442c02eb6c1e61d5be3f103110a5a 100644
--- a/silkaj/tui.py
+++ b/silkaj/tui.py
@@ -27,15 +27,12 @@ def display_amount(tx, message, amount, ud_value, currency_symbol):
     """
     Displays an amount in unit and relative reference.
     """
-    amount_UD = round((amount / ud_value), 2)
+    UD_amount = str(round((amount / ud_value), 2))
+    unit_amount = str(amount / 100)
     tx.append(
         [
-            message + " (unit|relative)",
-            "{unit_amount} {currency_symbol} | {UD_amount} UD {currency_symbol}".format(
-                unit_amount=str(amount / 100),
-                currency_symbol=currency_symbol,
-                UD_amount=str(amount_UD),
-            ),
+            f"{message} (unit|relative)",
+            f"{unit_amount} {currency_symbol} | {UD_amount} UD {currency_symbol}",
         ]
     )
 
@@ -44,10 +41,10 @@ def display_pubkey(tx, message, pubkey):
     """
     Displays a pubkey and the eventually associated id.
     """
-    tx.append([message + " (pubkey:checksum)", display_pubkey_and_checksum(pubkey)])
+    tx.append([f"{message} (pubkey:checksum)", display_pubkey_and_checksum(pubkey)])
     id = wot_tools.is_member(pubkey)
     if id:
-        tx.append([message + " (id)", id["uid"]])
+        tx.append([f"{message} (id)", id["uid"]])
 
 
 def display_pubkey_and_checksum(
@@ -58,8 +55,8 @@ def display_pubkey_and_checksum(
     returns `length` first chars of pubkey and checksum in short form.
     `length` defaults to SHORT_PUBKEY_SIZE.
     """
-    short_pubkey = pubkey[:length] + "…" if short else pubkey
-    return short_pubkey + ":" + ct.gen_checksum(pubkey)
+    short_pubkey = f"{pubkey[:length]}…" if short else pubkey
+    return f"{short_pubkey}:{ct.gen_checksum(pubkey)}"
 
 
 def send_doc_confirmation(document_name):