diff --git a/src/badguy/crusher.cpp b/src/badguy/crusher.cpp
index 51d2ba15c16..c7af75e8544 100644
--- a/src/badguy/crusher.cpp
+++ b/src/badguy/crusher.cpp
@@ -115,7 +115,7 @@ Crusher::collision(GameObject& other, const CollisionHit& hit)
     badguy->kill_fall();
   }
 
-  auto heavy_coin = dynamic_cast<HeavyCoin*>(&other);
+  const auto heavy_coin = dynamic_cast<HeavyCoin*>(&other);
   if (heavy_coin) {
     return ABORT_MOVE;
   }
diff --git a/src/gui/dialog.cpp b/src/gui/dialog.cpp
index 5e177a87be4..59d954206bd 100644
--- a/src/gui/dialog.cpp
+++ b/src/gui/dialog.cpp
@@ -229,12 +229,12 @@ Dialog::draw(DrawingContext& context)
   for (int i = 0; i < static_cast<int>(m_buttons.size()); ++i)
   {
     float segment_width = bg_rect.get_width() / static_cast<float>(m_buttons.size());
-    float button_width = segment_width;
     Vector pos(bg_rect.get_left() + segment_width/2.0f + static_cast<float>(i) * segment_width,
                bg_rect.get_bottom() - 12);
 
     if (i == m_selected_button)
     {
+      float button_width = segment_width;
       float button_height = 24.0f;
       float blink = (sinf(g_real_time * math::PI * 1.0f)/2.0f + 0.5f) * 0.5f + 0.25f;
       context.color().draw_filled_rect(Rectf(Vector(pos.x - button_width/2, pos.y - button_height/2),
diff --git a/src/object/custom_particle_system.cpp b/src/object/custom_particle_system.cpp
index fb7dace1bb3..feb6cb204bd 100644
--- a/src/object/custom_particle_system.cpp
+++ b/src/object/custom_particle_system.cpp
@@ -741,7 +741,6 @@ CustomParticleSystem::update(float dt_sec)
             auto c = get_collision(particle, Vector(particle->speedX, particle->speedY) * dt_sec);
 
             float speed_angle = atanf(-particle->speedY / particle->speedX);
-            float face_angle = atanf(c.slope_normal.y / c.slope_normal.x);
             if (c.slope_normal.x == 0.f && c.slope_normal.y == 0.f) {
               auto cX = get_collision(particle, Vector(particle->speedX, 0) * dt_sec);
               if (cX.left != cX.right)
@@ -750,6 +749,7 @@ CustomParticleSystem::update(float dt_sec)
               if (cY.top != cY.bottom)
                 particle->speedY *= -1;
             } else {
+              float face_angle = atanf(c.slope_normal.y / c.slope_normal.x);
               float dest_angle = face_angle * 2.f - speed_angle; // Reflect the angle around face_angle
               float dX = cosf(dest_angle),
                     dY = sinf(dest_angle);
diff --git a/src/scripting/wrapper.cpp b/src/scripting/wrapper.cpp
index 82b0ea0333e..9a9fad35e44 100644
--- a/src/scripting/wrapper.cpp
+++ b/src/scripting/wrapper.cpp
@@ -1251,7 +1251,7 @@ static SQInteger Clouds_set_amount_wrapper(HSQUIRRELVM vm)
 
 static SQInteger ConveyorBelt_release_hook(SQUserPointer ptr, SQInteger )
 {
-  auto _this = reinterpret_cast<scripting::ConveyorBelt*> (ptr);
+  scripting::ConveyorBelt* _this = reinterpret_cast<scripting::ConveyorBelt*> (ptr);
   delete _this;
   return 0;
 }
@@ -1263,11 +1263,7 @@ static SQInteger ConveyorBelt_start_wrapper(HSQUIRRELVM vm)
     sq_throwerror(vm, _SC("'start' called without instance"));
     return SQ_ERROR;
   }
-  auto _this = reinterpret_cast<scripting::ConveyorBelt*> (data);
-
-  if (_this == nullptr) {
-    return SQ_ERROR;
-  }
+  scripting::ConveyorBelt* _this = reinterpret_cast<scripting::ConveyorBelt*> (data);
 
 
   try {
@@ -1292,11 +1288,7 @@ static SQInteger ConveyorBelt_stop_wrapper(HSQUIRRELVM vm)
     sq_throwerror(vm, _SC("'stop' called without instance"));
     return SQ_ERROR;
   }
-  auto _this = reinterpret_cast<scripting::ConveyorBelt*> (data);
-
-  if (_this == nullptr) {
-    return SQ_ERROR;
-  }
+  scripting::ConveyorBelt* _this = reinterpret_cast<scripting::ConveyorBelt*> (data);
 
 
   try {
@@ -1321,11 +1313,7 @@ static SQInteger ConveyorBelt_move_left_wrapper(HSQUIRRELVM vm)
     sq_throwerror(vm, _SC("'move_left' called without instance"));
     return SQ_ERROR;
   }
-  auto _this = reinterpret_cast<scripting::ConveyorBelt*> (data);
-
-  if (_this == nullptr) {
-    return SQ_ERROR;
-  }
+  scripting::ConveyorBelt* _this = reinterpret_cast<scripting::ConveyorBelt*> (data);
 
 
   try {
@@ -1350,11 +1338,7 @@ static SQInteger ConveyorBelt_move_right_wrapper(HSQUIRRELVM vm)
     sq_throwerror(vm, _SC("'move_right' called without instance"));
     return SQ_ERROR;
   }
-  auto _this = reinterpret_cast<scripting::ConveyorBelt*> (data);
-
-  if (_this == nullptr) {
-    return SQ_ERROR;
-  }
+  scripting::ConveyorBelt* _this = reinterpret_cast<scripting::ConveyorBelt*> (data);
 
 
   try {
@@ -1379,11 +1363,7 @@ static SQInteger ConveyorBelt_set_speed_wrapper(HSQUIRRELVM vm)
     sq_throwerror(vm, _SC("'set_speed' called without instance"));
     return SQ_ERROR;
   }
-  auto _this = reinterpret_cast<scripting::ConveyorBelt*> (data);
-
-  if (_this == nullptr) {
-    return SQ_ERROR;
-  }
+  scripting::ConveyorBelt* _this = reinterpret_cast<scripting::ConveyorBelt*> (data);
 
   SQFloat arg0;
   if(SQ_FAILED(sq_getfloat(vm, 2, &arg0))) {
@@ -1392,7 +1372,7 @@ static SQInteger ConveyorBelt_set_speed_wrapper(HSQUIRRELVM vm)
   }
 
   try {
-    _this->set_speed(static_cast<float> (arg0));
+    _this->set_speed(arg0);
 
     return 0;
 
@@ -14051,35 +14031,35 @@ void register_supertux_wrapper(HSQUIRRELVM v)
   }
   sq_pushstring(v, "start", -1);
   sq_newclosure(v, &ConveyorBelt_start_wrapper, 0);
-  sq_setparamscheck(v, SQ_MATCHTYPEMASKSTRING, "x|t");
+  sq_setparamscheck(v, SQ_MATCHTYPEMASKSTRING, ".");
   if(SQ_FAILED(sq_createslot(v, -3))) {
     throw SquirrelError(v, "Couldn't register function 'start'");
   }
 
   sq_pushstring(v, "stop", -1);
   sq_newclosure(v, &ConveyorBelt_stop_wrapper, 0);
-  sq_setparamscheck(v, SQ_MATCHTYPEMASKSTRING, "x|t");
+  sq_setparamscheck(v, SQ_MATCHTYPEMASKSTRING, ".");
   if(SQ_FAILED(sq_createslot(v, -3))) {
     throw SquirrelError(v, "Couldn't register function 'stop'");
   }
 
   sq_pushstring(v, "move_left", -1);
   sq_newclosure(v, &ConveyorBelt_move_left_wrapper, 0);
-  sq_setparamscheck(v, SQ_MATCHTYPEMASKSTRING, "x|t");
+  sq_setparamscheck(v, SQ_MATCHTYPEMASKSTRING, ".");
   if(SQ_FAILED(sq_createslot(v, -3))) {
     throw SquirrelError(v, "Couldn't register function 'move_left'");
   }
 
   sq_pushstring(v, "move_right", -1);
   sq_newclosure(v, &ConveyorBelt_move_right_wrapper, 0);
-  sq_setparamscheck(v, SQ_MATCHTYPEMASKSTRING, "x|t");
+  sq_setparamscheck(v, SQ_MATCHTYPEMASKSTRING, ".");
   if(SQ_FAILED(sq_createslot(v, -3))) {
     throw SquirrelError(v, "Couldn't register function 'move_right'");
   }
 
   sq_pushstring(v, "set_speed", -1);
   sq_newclosure(v, &ConveyorBelt_set_speed_wrapper, 0);
-  sq_setparamscheck(v, SQ_MATCHTYPEMASKSTRING, "x|tn");
+  sq_setparamscheck(v, SQ_MATCHTYPEMASKSTRING, ".b|n");
   if(SQ_FAILED(sq_createslot(v, -3))) {
     throw SquirrelError(v, "Couldn't register function 'set_speed'");
   }
diff --git a/src/supertux/gameconfig.cpp b/src/supertux/gameconfig.cpp
index a11921f4193..e6ead3275c8 100644
--- a/src/supertux/gameconfig.cpp
+++ b/src/supertux/gameconfig.cpp
@@ -525,7 +525,7 @@ bool
 Config::is_christmas() const
 {
   std::time_t time = std::time(nullptr);
-  std::tm* now = std::localtime(&time);
+  const std::tm* now = std::localtime(&time);
 
   /* Activate Christmas mode from Dec 6th until Dec 31st. */
   return now->tm_mday >= 6 && now->tm_mon == 11;