diff --git a/pySim-trace.py b/pySim-trace.py
index eb29ed1a..91f50a34 100755
--- a/pySim-trace.py
+++ b/pySim-trace.py
@@ -182,7 +182,7 @@ if __name__ == '__main__':
 
     opts = option_parser.parse_args()
 
-    logger.info('Opening source %s...' % opts.source)
+    logger.info('Opening source %s...', opts.source)
     if opts.source == 'gsmtap-udp':
         s = GsmtapApduSource(opts.bind_ip, opts.bind_port)
     elif opts.source == 'rspro-pyshark-pcap':
diff --git a/pySim/apdu/ts_102_221.py b/pySim/apdu/ts_102_221.py
index 2d3ad82f..443ae1e2 100644
--- a/pySim/apdu/ts_102_221.py
+++ b/pySim/apdu/ts_102_221.py
@@ -77,7 +77,7 @@ class UiccSelect(ApduCommand, n='SELECT', ins=0xA4, cla=['0X', '4X', '6X']):
                             pass
                         # iterate to next element in path
                         continue
-                logger.warning('SELECT UNKNOWN FID %s (%s)' % (file_hex, '/'.join([b2h(x) for x in path])))
+                logger.warning('SELECT UNKNOWN FID %s (%s)', file_hex, '/'.join([b2h(x) for x in path]))
         elif mode == 'df_ef_or_mf_by_file_id':
             if len(self.cmd_data) != 2:
                 raise ValueError('Expecting a 2-byte FID')
@@ -91,7 +91,7 @@ class UiccSelect(ApduCommand, n='SELECT', ins=0xA4, cla=['0X', '4X', '6X']):
                     #print("\tSELECT %s FAILED" % sels[file_hex])
                     pass
             else:
-                logger.warning('SELECT UNKNOWN FID %s' % (file_hex))
+                logger.warning('SELECT UNKNOWN FID %s', file_hex)
         elif mode == 'df_name':
             # Select by AID (can be sub-string!)
             aid = self.cmd_dict['body']
@@ -102,7 +102,7 @@ class UiccSelect(ApduCommand, n='SELECT', ins=0xA4, cla=['0X', '4X', '6X']):
                 lchan.selected_file = lchan.selected_adf
                 #print("\tSELECT AID %s" % adf)
             else:
-                logger.warning('SELECT UNKNOWN AID %s' % aid)
+                logger.warning('SELECT UNKNOWN AID %s', aid)
                 pass
         else:
             raise ValueError('Select Mode %s not implemented' % mode)
@@ -490,7 +490,7 @@ class RetrieveData(ApduCommand, n='RETRIEVE DATA', ins=0xCB, cla=['8X', 'CX', 'E
         elif self.p2 & 0xdf == 0x40:
             c['mode'] = 'retransmit_previous_block'
         else:
-            logger.warning('%s: invalid P2=%02x' % (self, self.p2))
+            logger.warning('%s: invalid P2=%02x', self, self.p2)
         return c
 
     def _decode_cmd(self):
diff --git a/pySim/apdu_source/pyshark_rspro.py b/pySim/apdu_source/pyshark_rspro.py
index 8c614ffc..039326ad 100644
--- a/pySim/apdu_source/pyshark_rspro.py
+++ b/pySim/apdu_source/pyshark_rspro.py
@@ -89,7 +89,7 @@ class _PysharkRspro(ApduSource):
             bsl = self.get_bank_slot(bank_slot)
             self._set_or_verify_bank_slot(bsl)
             data = modem2card.get_field('data').replace(':','')
-            logger.debug("C(%u:%u) -> B(%u:%u): %s" % (csl[0], csl[1], bsl[0], bsl[1], data))
+            logger.debug("C(%u:%u) -> B(%u:%u): %s", csl[0], csl[1], bsl[0], bsl[1], data)
             # store the CMD portion until the RSP portion arrives later
             self.cmd_tpdu = h2b(data)
         elif msg_type == '13': # tpduCardToModem
@@ -101,7 +101,7 @@ class _PysharkRspro(ApduSource):
             bsl = self.get_bank_slot(bank_slot)
             self._set_or_verify_bank_slot(bsl)
             data = card2modem.get_field('data').replace(':','')
-            logger.debug("C(%u:%u) <- B(%u:%u): %s" % (csl[0], csl[1], bsl[0], bsl[1], data))
+            logger.debug("C(%u:%u) <- B(%u:%u): %s", csl[0], csl[1], bsl[0], bsl[1], data)
             rsp_tpdu = h2b(data)
             if self.cmd_tpdu:
                 # combine this R-TPDU with the C-TPDU we saw earlier