diff --git a/spot/kripke/kripkegraph.hh b/spot/kripke/kripkegraph.hh
index 348e1ccf5..d6292c070 100644
--- a/spot/kripke/kripkegraph.hh
+++ b/spot/kripke/kripkegraph.hh
@@ -64,8 +64,7 @@ namespace spot
 
     virtual size_t hash() const override
     {
-      return
-        reinterpret_cast<const char*>(this) - static_cast<const char*>(nullptr);
+      return reinterpret_cast<size_t>(this);
     }
 
     virtual kripke_graph_state*
diff --git a/spot/misc/hash.hh b/spot/misc/hash.hh
index 94f603b7c..b99c4ab53 100644
--- a/spot/misc/hash.hh
+++ b/spot/misc/hash.hh
@@ -48,8 +48,7 @@ namespace spot
 
     size_t operator()(const T* p) const noexcept
     {
-      return knuth32_hash(reinterpret_cast<const char*>(p)
-                          - static_cast<const char*>(nullptr));
+      return knuth32_hash(reinterpret_cast<size_t>(p));
     }
   };
 
diff --git a/spot/twa/acc.hh b/spot/twa/acc.hh
index 761433f54..455850f35 100644
--- a/spot/twa/acc.hh
+++ b/spot/twa/acc.hh
@@ -1670,6 +1670,7 @@ namespace spot
 #ifndef SWIG
       rs_pair() = default;
       rs_pair(const rs_pair&) = default;
+      rs_pair& operator=(const rs_pair&) = default;
 #endif
 
       rs_pair(acc_cond::mark_t fin, acc_cond::mark_t inf) noexcept:
diff --git a/spot/twa/taatgba.cc b/spot/twa/taatgba.cc
index 416028e37..1ae35ff1b 100644
--- a/spot/twa/taatgba.cc
+++ b/spot/twa/taatgba.cc
@@ -105,7 +105,7 @@ namespace spot
     taa_tgba::state_set::const_iterator it = s_->begin();
     while (it != s_->end())
     {
-      res ^= reinterpret_cast<const char*>(*it++) - static_cast<char*>(nullptr);
+      res ^= reinterpret_cast<size_t>(*it++);
       res = wang32_hash(res);
     }
     return res;
diff --git a/spot/twa/twagraph.hh b/spot/twa/twagraph.hh
index 683fa32c8..c6222871e 100644
--- a/spot/twa/twagraph.hh
+++ b/spot/twa/twagraph.hh
@@ -70,8 +70,7 @@ namespace spot
 
     virtual size_t hash() const override
     {
-      return
-        reinterpret_cast<const char*>(this) - static_cast<const char*>(nullptr);
+      return reinterpret_cast<size_t>(this);
     }
 
     virtual twa_graph_state*
diff --git a/tests/core/ngraph.cc b/tests/core/ngraph.cc
index 021e66452..0a64f5f73 100644
--- a/tests/core/ngraph.cc
+++ b/tests/core/ngraph.cc
@@ -372,8 +372,7 @@ public:
 
   size_t hash() const override
   {
-    return
-      reinterpret_cast<const char*>(this) - static_cast<const char*>(nullptr);
+    return reinterpret_cast<size_t>(this);
   }
 
   my_state* clone() const override