diff --git a/removeads.py b/removeads.py
index a64f687..a99c2e3 100755
--- a/removeads.py
+++ b/removeads.py
@@ -1579,29 +1579,29 @@ class AVCDecoderConfiguration:
     def merge(self, config):
         # Check config compatibility
         if  self.configuration_version != config.configuration_version:
-            raise ValueError('Configuration versions are different: %d vs %s' %\
-                            (self.configuration_version, config.configuration_version))
+            raise ValueError(f'Configuration versions are different: {self.configuration_version:d}\
+                             vs {config.configuration_version:d}')
         if self.avc_profile_indication != config.avc_profile_indication:
-            raise ValueError('AVC profiles are different: %d vs %s' %\
-                            (self.avc_profile_indication, config.avc_profile_indication))
+            raise ValueError(f'AVC profiles are different: {self.avc_profile_indication:d} vs \
+                            {config.avc_profile_indication:d}')
         if self.profile_compatibility != config.profile_compatibility:
-            raise ValueError('Profile compatilities are different: %d vs %s' %\
-                            (self.profile_compatibility, config.profile_compatibility))
+            raise ValueError(f'Profile compatilities are different: {self.profile_compatibility:d} \
+                            vs {config.profile_compatibility:d}')
         if self.avc_level_indication != config.avc_level_indication:
-            raise ValueError('Level indications are different: %d vs %s' %\
-                (self.avc_level_indication, config.avc_level_indication))
+            raise ValueError(f'Level indications are different: {self.avc_level_indication:d} vs \
+                            {config.avc_level_indication:d}')
         if self.length_size_minus_one != config.length_size_minus_one:
-            raise ValueError('Length units are different: %d vs %s' %\
-                            (self.length_size_minus_one, config.length_size_minus_one))
+            raise ValueError(f'Length units are different: {self.length_size_minus_one:d} vs \
+                            {config.length_size_minus_one:d}')
         if self.chroma_format != config.chroma_format:
-            raise ValueError('Colour format are different: %d vs %s' %\
-                            (self.chroma_format, config.chroma_format))
+            raise ValueError(f'Colour format are different: {self.chroma_format:d} vs \
+                            {config.chroma_format:d}')
         if self.bit_depth_luma_minus8 != config.bit_depth_luma_minus8:
-            raise ValueError('Depth of luminance are different: %d vs %s' %\
-                            (self.bit_depth_luma_minus8, config.bit_depth_luma_minus8))
+            raise ValueError(f'Depth of luminance are different: {self.bit_depth_luma_minus8:d} vs \
+                            {config.bit_depth_luma_minus8:d}')
         if self.bit_depth_chroma_minus8 != config.bit_depth_chroma_minus8:
-            raise ValueError('Depth of chromaticity are different: %d vs %s' %\
-                (self.bit_depth_chroma_minus8, config.bit_depth_luma_minus8))
+            raise ValueError(f'Depth of chromaticity are different: \
+                            {self.bit_depth_chroma_minus8:d} vs {config.bit_depth_luma_minus8:d}')
 
         for spsid in config.sps:
             sps = config.sps[spsid]