diff --git a/include/lol/private/math/matrix.h b/include/lol/private/math/matrix.h
index d64aa2b0..743b94fd 100644
--- a/include/lol/private/math/matrix.h
+++ b/include/lol/private/math/matrix.h
@@ -1,7 +1,7 @@
 //
 //  Lol Engine
 //
-//  Copyright © 2010—2020 Sam Hocevar <sam@hocevar.net>
+//  Copyright © 2010–2023 Sam Hocevar <sam@hocevar.net>
 //
 //  Lol Engine is free software. It comes without any warranty, to
 //  the extent permitted by applicable law. You can redistribute it
@@ -20,6 +20,7 @@
 #include "ops.h"
 #include <lol/vector> // lol::vec_t
 #include <ostream>    // std::ostream
+#include <tuple>      // std::tuple
 #include <cmath>      // std::fabs
 
 namespace lol
diff --git a/include/lol/private/math/polynomial.h b/include/lol/private/math/polynomial.h
index ea05e5dc..5507747f 100644
--- a/include/lol/private/math/polynomial.h
+++ b/include/lol/private/math/polynomial.h
@@ -1,7 +1,7 @@
 //
 //  Lol Engine
 //
-//  Copyright © 2010—2020 Sam Hocevar <sam@hocevar.net>
+//  Copyright © 2010–2023 Sam Hocevar <sam@hocevar.net>
 //
 //  Lol Engine is free software. It comes without any warranty, to
 //  the extent permitted by applicable law. You can redistribute it
@@ -27,6 +27,7 @@
 #include <tuple>      // std::tuple
 #include <cassert>    // assert()
 #include <cmath>      // sqrt(), cbrt(), acos()
+#include <cstddef>    // std::size_t
 
 namespace lol
 {
@@ -265,13 +266,13 @@ struct [[nodiscard]] polynomial
         return {};
     }
 
-    /* Access individual coefficients. This is read-only and returns a
-     * copy because we cannot let the user mess with the integrity of
-     * the structure (i.e. the guarantee that the leading coefficient
-     * remains non-zero). */
-    [[nodiscard]] inline T operator[](ptrdiff_t n) const
+    // Access individual coefficients. This is read-only and returns a
+    // copy because we cannot let the user mess with the integrity of
+    // the structure (i.e. the guarantee that the leading coefficient
+    // remains non-zero).
+    [[nodiscard]] inline T operator[](std::size_t n) const
     {
-        if (n < 0 || n > degree())
+        if (degree() < 0 || n > std::size_t(degree()))
             return T(0);
 
         return m_coefficients[n];
diff --git a/include/lol/private/math/vector.h b/include/lol/private/math/vector.h
index 3edda74f..deb7742c 100644
--- a/include/lol/private/math/vector.h
+++ b/include/lol/private/math/vector.h
@@ -1,7 +1,7 @@
 //
 //  Lol Engine
 //
-//  Copyright © 2010—2020 Sam Hocevar <sam@hocevar.net>
+//  Copyright © 2010–2023 Sam Hocevar <sam@hocevar.net>
 //
 //  Lol Engine is free software. It comes without any warranty, to
 //  the extent permitted by applicable law. You can redistribute it
@@ -103,8 +103,9 @@ private:
  */
 
 #define LOL_COMMON_MEMBER_OPS(first) \
-    inline T& operator[](size_t n) { return (&this->first)[n]; } \
-    inline T const& operator[](size_t n) const { return (&this->first)[n]; } \
+    /* Use reinterpret_cast because static_cast is illegal here */ \
+    inline T& operator[](size_t n) { return reinterpret_cast<T*>(this)[n]; } \
+    inline T const& operator[](size_t n) const { return reinterpret_cast<T const*>(this)[n]; } \
     \
     /* An explicit assignment operator is now mandatory */ \
     inline type & operator =(type const &that) \