diff --git a/src/insert_completer.hh b/src/insert_completer.hh
index 64c547580..2de8a0004 100644
--- a/src/insert_completer.hh
+++ b/src/insert_completer.hh
@@ -23,7 +23,7 @@ struct InsertCompleterDesc
     { return mode == other.mode and param == other.param; }
 
     bool operator!=(const InsertCompleterDesc& other) const
-    { return !(*this == other); }
+    { return not (*this == other); }
 
     Mode mode;
     Optional<String> param;
diff --git a/src/line_modification.cc b/src/line_modification.cc
index ac2bd487b..bd31eb168 100644
--- a/src/line_modification.cc
+++ b/src/line_modification.cc
@@ -110,7 +110,7 @@ UnitTest test_line_modifications{[]()
         buffer.erase(buffer.iterator_at({1, 0}), buffer.iterator_at({2, 0}));
 
         auto modifs = compute_line_modifications(buffer, ts);
-        kak_assert(modifs.size() == 1 && modifs[0] == LineModification{ 1 COMMA 1 COMMA 1 COMMA 0 });
+        kak_assert(modifs.size() == 1 and modifs[0] == LineModification{ 1 COMMA 1 COMMA 1 COMMA 0 });
     }
 
     {
@@ -119,7 +119,7 @@ UnitTest test_line_modifications{[]()
         buffer.insert(buffer.iterator_at({1, 7}), "line 3");
 
         auto modifs = compute_line_modifications(buffer, ts);
-        kak_assert(modifs.size() == 1 && modifs[0] == LineModification{ 2 COMMA 2 COMMA 0 COMMA 1 });
+        kak_assert(modifs.size() == 1 and modifs[0] == LineModification{ 2 COMMA 2 COMMA 0 COMMA 1 });
     }
 
     {
@@ -130,7 +130,7 @@ UnitTest test_line_modifications{[]()
         buffer.erase(buffer.iterator_at({0, 0}), buffer.iterator_at({1, 0}));
 
         auto modifs = compute_line_modifications(buffer, ts);
-        kak_assert(modifs.size() == 1 && modifs[0] == LineModification{ 0 COMMA 0 COMMA 2 COMMA 2 });
+        kak_assert(modifs.size() == 1 and modifs[0] == LineModification{ 0 COMMA 0 COMMA 2 COMMA 2 });
     }
 
     {
@@ -142,13 +142,13 @@ UnitTest test_line_modifications{[]()
         buffer.erase(buffer.iterator_at({0,0}), buffer.iterator_at({1,0}));
         {
             auto modifs = compute_line_modifications(buffer, ts);
-            kak_assert(modifs.size() == 1 && modifs[0] == LineModification{ 0 COMMA 0 COMMA 4 COMMA 3 });
+            kak_assert(modifs.size() == 1 and modifs[0] == LineModification{ 0 COMMA 0 COMMA 4 COMMA 3 });
         }
         buffer.insert(buffer.iterator_at({3,0}), "newline 4\n");
 
         {
             auto modifs = compute_line_modifications(buffer, ts);
-            kak_assert(modifs.size() == 1 && modifs[0] == LineModification{ 0 COMMA 0 COMMA 4 COMMA 4 });
+            kak_assert(modifs.size() == 1 and modifs[0] == LineModification{ 0 COMMA 0 COMMA 4 COMMA 4 });
         }
     }
 
@@ -159,7 +159,7 @@ UnitTest test_line_modifications{[]()
         buffer.insert(buffer.iterator_at({0,1}), "e");
         buffer.insert(buffer.iterator_at({0,2}), "w");
         auto modifs = compute_line_modifications(buffer, ts);
-        kak_assert(modifs.size() == 1 && modifs[0] == LineModification{ 0 COMMA 0 COMMA 1 COMMA 1 });
+        kak_assert(modifs.size() == 1 and modifs[0] == LineModification{ 0 COMMA 0 COMMA 1 COMMA 1 });
     }
 }};
 
diff --git a/src/selection.hh b/src/selection.hh
index 26a7865c8..c576bf41d 100644
--- a/src/selection.hh
+++ b/src/selection.hh
@@ -119,7 +119,7 @@ struct SelectionList
     size_t size() const { return m_selections.size(); }
 
     bool operator==(const SelectionList& other) const { return m_buffer == other.m_buffer and m_selections == other.m_selections; }
-    bool operator!=(const SelectionList& other) const { return !((*this) == other); }
+    bool operator!=(const SelectionList& other) const { return not ((*this) == other); }
 
     void sort_and_merge_overlapping();
 
diff --git a/src/units.hh b/src/units.hh
index 21c583b29..fbb75c225 100644
--- a/src/units.hh
+++ b/src/units.hh
@@ -105,7 +105,7 @@ public:
 
     [[gnu::always_inline]]
     constexpr bool operator!() const
-    { return !m_value; }
+    { return not m_value; }
 
     [[gnu::always_inline]]
     explicit constexpr operator ValueType() const { return m_value; }