diff --git a/pyproject.toml b/pyproject.toml
index 5b66302e74..93b6047edf 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -105,7 +105,7 @@ quote-style = 'single'
 explicit-preview-rules = true
 ignore = [
     'E402', 'E741',
-    'UP012', 'UP030', 'C413', 'C420', 'PIE790', 'ISC003', 'FURB122', 'FURB166', 'FURB167', 'FURB116',
+    'UP012', 'UP030', 'C413', 'C420', 'PIE790', 'ISC003', 'FURB122', 'FURB166', 'FURB167',
     'RUF001', 'RUF002', 'RUF003', 'RUF005', 'RUF012', 'RUF013', 'RUF015', 'RUF031', 'RUF100',
     'PLE1205', 'PLW0602', 'PLW0603', 'PLW1510', 'PLW1641', 'PLW2901', 'PLC0415',
     'PLR0911', 'PLR0912', 'PLR0913', 'PLR0914', 'PLR0915', 'PLR0916', 'PLR0917', 'PLR1702', 'PLR1704', 'PLR2004', 'PLR6301',
diff --git a/src/calibre/ebooks/lrf/html/color_map.py b/src/calibre/ebooks/lrf/html/color_map.py
index 1fc4464256..132c36b931 100644
--- a/src/calibre/ebooks/lrf/html/color_map.py
+++ b/src/calibre/ebooks/lrf/html/color_map.py
@@ -107,7 +107,7 @@ def lrs_color(html_color):
         return '0x00'+match.group(1)+match.group(2)+match.group(3)
     match = rgb_pat.search(hcol)
     if match:
-        return '0x00'+hex(int(match.group(1)))[2:]+hex(int(match.group(2)))[2:]+hex(int(match.group(3)))[2:]
+        return f'0x00{int(match.group(1)):x}{int(match.group(2)):x}{int(match.group(3)):x}'
     if hcol in NAME_MAP:
         return NAME_MAP[hcol].replace('#', '0x00')
     return '0x00000000'
diff --git a/src/calibre/ebooks/mobi/debug/__init__.py b/src/calibre/ebooks/mobi/debug/__init__.py
index 673178a74e..93d76df8a1 100644
--- a/src/calibre/ebooks/mobi/debug/__init__.py
+++ b/src/calibre/ebooks/mobi/debug/__init__.py
@@ -8,5 +8,5 @@ __docformat__ = 'restructuredtext en'
 
 def format_bytes(byts):
     byts = bytearray(byts)
-    byts = [hex(b)[2:] for b in byts]
+    byts = [f'{b:x}' for b in byts]
     return ' '.join(byts)
diff --git a/src/calibre/ebooks/mobi/debug/headers.py b/src/calibre/ebooks/mobi/debug/headers.py
index 041c04d64b..d98e44680e 100644
--- a/src/calibre/ebooks/mobi/debug/headers.py
+++ b/src/calibre/ebooks/mobi/debug/headers.py
@@ -461,7 +461,7 @@ class MOBIHeader:  # {{{
         a(f'Huffman record count: {self.huffman_record_count}')
         r('Huffman table offset', 'datp_record_offset')
         a(f'Huffman table length: {self.datp_record_count!r}')
-        a(f'EXTH flags: {bin(self.exth_flags)[2:]} ({self.has_exth})')
+        a(f'EXTH flags: {self.exth_flags:b} ({self.has_exth})')
         if self.has_drm_data:
             a(f'Unknown3: {self.unknown3!r}')
             r('DRM Offset', 'drm_offset')
diff --git a/src/calibre/ebooks/mobi/debug/mobi6.py b/src/calibre/ebooks/mobi/debug/mobi6.py
index d4fe7dd44a..570f621e56 100644
--- a/src/calibre/ebooks/mobi/debug/mobi6.py
+++ b/src/calibre/ebooks/mobi/debug/mobi6.py
@@ -593,7 +593,7 @@ class TBSIndexing:  # {{{
                     ans.append(f'\t\tIndex Entry: {x.index} (Parent index: {x.parent_index}, Depth: {x.depth}, Offset: {x.offset}, Size: {x.size}) [{x.label}]')
 
         def bin4(num):
-            ans = bin(num)[2:]
+            ans = f'{num:b}'
             return as_bytes('0'*(4-len(ans)) + ans)
 
         def repr_extra(x):
@@ -620,7 +620,7 @@ class TBSIndexing:  # {{{
                     print(f'Failed to decode TBS bytes for record: {r.idx}')
                 ans += a
             if byts:
-                sbyts = tuple(hex(b)[2:] for b in byts)
+                sbyts = tuple(f'{b:x}' for b in byts)
                 ans.append('Remaining bytes: {}'.format(' '.join(sbyts)))
 
         ans.append('')
diff --git a/src/calibre/ebooks/mobi/reader/index.py b/src/calibre/ebooks/mobi/reader/index.py
index 70af01b5e0..6a695914ef 100644
--- a/src/calibre/ebooks/mobi/reader/index.py
+++ b/src/calibre/ebooks/mobi/reader/index.py
@@ -39,7 +39,7 @@ class NotATAGXSection(InvalidFile):
 
 def format_bytes(byts):
     byts = bytearray(byts)
-    byts = [hex(b)[2:] for b in byts]
+    byts = [f'{b:x}' for b in byts]
     return ' '.join(byts)
 
 
diff --git a/src/calibre/ebooks/mobi/utils.py b/src/calibre/ebooks/mobi/utils.py
index 09be029b3d..15ea4b85cb 100644
--- a/src/calibre/ebooks/mobi/utils.py
+++ b/src/calibre/ebooks/mobi/utils.py
@@ -80,7 +80,7 @@ def encode_number_as_hex(num):
     The bytes that follow are simply the hexadecimal representation of the
     number.
     '''
-    num = hex(num)[2:].upper().encode('ascii')
+    num = f'{num:X}'.encode('ascii')
     nlen = len(num)
     if nlen % 2 != 0:
         num = b'0'+num
diff --git a/src/calibre/ebooks/pdf/render/fonts.py b/src/calibre/ebooks/pdf/render/fonts.py
index dec0355783..d6bf5e1b4a 100644
--- a/src/calibre/ebooks/pdf/render/fonts.py
+++ b/src/calibre/ebooks/pdf/render/fonts.py
@@ -59,7 +59,7 @@ class FontStream(Stream):
 
 
 def to_hex_string(c):
-    ans = hex(int(c))[2:]
+    ans = f'{int(c):x}'
     if isinstance(ans, bytes):
         ans = ans.decode('ascii')
     return ans.rjust(4, '0')