diff --git a/src/pbs.cpp b/src/pbs.cpp
index e7d0473933..7c48cb8cda 100644
--- a/src/pbs.cpp
+++ b/src/pbs.cpp
@@ -98,15 +98,15 @@ bool TryReserveRailTrackdir(const Train *v, TileIndex tile, Trackdir td, bool tr
 /**
  * Try to reserve a specific track on a tile
  * @param tile the tile
- * @param t the track
+ * @param track the track
  * @param trigger_stations whether to call station randomisation trigger
  * @return \c true if reservation was successful, i.e. the track was
  *     free and didn't cross any other reserved tracks.
  */
-bool TryReserveRailTrack(TileIndex tile, Track t, bool trigger_stations)
+bool TryReserveRailTrack(TileIndex tile, Track track, bool trigger_stations)
 {
-	assert_msg_tile((TrackStatusToTrackBits(GetTileTrackStatus(tile, TRANSPORT_RAIL, 0)) & TrackToTrackBits(t)) != 0, tile,
-			"%X, %X, %X", TrackStatusToTrackBits(GetTileTrackStatus(tile, TRANSPORT_RAIL, 0)), t, TrackToTrackBits(t));
+	assert_msg_tile((TrackStatusToTrackBits(GetTileTrackStatus(tile, TRANSPORT_RAIL, 0)) & TrackToTrackBits(track)) != 0, tile,
+			"%X, %X, %X", TrackStatusToTrackBits(GetTileTrackStatus(tile, TRANSPORT_RAIL, 0)), track, TrackToTrackBits(track));
 
 	if (_settings_client.gui.show_track_reservation) {
 		/* show the reserved rail if needed */
@@ -119,7 +119,7 @@ bool TryReserveRailTrack(TileIndex tile, Track t, bool trigger_stations)
 
 	switch (GetTileType(tile)) {
 		case MP_RAILWAY:
-			if (IsPlainRail(tile)) return TryReserveTrack(tile, t);
+			if (IsPlainRail(tile)) return TryReserveTrack(tile, track);
 			if (IsRailDepot(tile)) {
 				if (!HasDepotReservation(tile)) {
 					SetDepotReservation(tile, true);
@@ -166,7 +166,7 @@ bool TryReserveRailTrack(TileIndex tile, Track t, bool trigger_stations)
 					return true;
 				}
 				if (IsBridge(tile)) {
-					if (TryReserveRailBridgeHead(tile, t)) {
+					if (TryReserveRailBridgeHead(tile, track)) {
 						MarkBridgeOrTunnelDirtyOnReservationChange(tile, VMDF_NOT_MAP_MODE);
 						return true;
 					}
diff --git a/src/tracerestrict_gui.cpp b/src/tracerestrict_gui.cpp
index 90b2cd0438..eec34c3e1b 100644
--- a/src/tracerestrict_gui.cpp
+++ b/src/tracerestrict_gui.cpp
@@ -1555,9 +1555,9 @@ static void DrawInstructionString(const TraceRestrictProgram *prog, TraceRestric
 
 					case TRPPAF_PRESET: {
 						instruction_string = STR_TRACE_RESTRICT_PF_PENALTY_ITEM_PRESET;
-						uint16 index = GetTraceRestrictValue(item);
-						assert(index < TRPPPI_END);
-						SetDParam(0, _pf_penalty_dropdown_str[index]);
+						uint16 idx = GetTraceRestrictValue(item);
+						assert(idx < TRPPPI_END);
+						SetDParam(0, _pf_penalty_dropdown_str[idx]);
 						break;
 					}
 
diff --git a/src/tree_cmd.cpp b/src/tree_cmd.cpp
index 93d93de572..80c842258f 100644
--- a/src/tree_cmd.cpp
+++ b/src/tree_cmd.cpp
@@ -537,7 +537,7 @@ void GenerateTrees()
 
 /**
  * Plant a tree.
- * @param tile end tile of area-drag
+ * @param end_tile end tile of area-drag
  * @param flags type of operation
  * @param p1 various bitstuffed data.
  * - p1 = (bit 0 -  7) - tree type, TREE_INVALID means random.
@@ -546,7 +546,7 @@ void GenerateTrees()
  * @param text unused
  * @return the cost of this operation or an error
  */
-CommandCost CmdPlantTree(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
+CommandCost CmdPlantTree(TileIndex end_tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
 {
 	StringID msg = INVALID_STRING_ID;
 	CommandCost cost(EXPENSES_OTHER);
@@ -559,7 +559,7 @@ CommandCost CmdPlantTree(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 	Company *c = (_game_mode != GM_EDITOR) ? Company::GetIfValid(_current_company) : nullptr;
 	int limit = (c == nullptr ? INT32_MAX : GB(c->tree_limit, 16, 16));
 
-	OrthogonalOrDiagonalTileIterator iter(tile, p2, HasBit(p1, 8));
+	OrthogonalOrDiagonalTileIterator iter(end_tile, p2, HasBit(p1, 8));
 	for (; *iter != INVALID_TILE; ++iter) {
 		TileIndex tile = *iter;
 		switch (GetTileType(tile)) {
diff --git a/src/viewport.cpp b/src/viewport.cpp
index 28f9c1d9ea..9b0290b4d5 100644
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -548,11 +548,11 @@ struct ViewportRedrawRegion {
 
 static std::vector<ViewportRedrawRegion> _vp_redraw_regions;
 
-static void DoViewportRedrawRegions(const Window *w, int left, int top, int width, int height)
+static void DoViewportRedrawRegions(const Window *w_start, int left, int top, int width, int height)
 {
 	if (width <= 0 || height <= 0) return;
 
-	for (const Window *w : Window::IterateFromBack<const Window>(w)) {
+	for (const Window *w : Window::IterateFromBack<const Window>(w_start)) {
 		if (left + width > w->left &&
 				w->left + w->width > left &&
 				top + height > w->top &&
@@ -645,7 +645,7 @@ static void DoSetViewportPositionFillRegion(int left, int top, int width, int he
 	DrawOverlappedWindowForAll(left, top, left + width, top + height);
 };
 
-static void DoSetViewportPosition(Window *w, const int left, const int top, const int width, const int height)
+static void DoSetViewportPosition(Window *w, const int vp_left, const int vp_top, const int vp_width, const int vp_height)
 {
 	const int xo = _vp_move_offs.x;
 	const int yo = _vp_move_offs.y;
@@ -654,9 +654,9 @@ static void DoSetViewportPosition(Window *w, const int left, const int top, cons
 	IncrementWindowUpdateNumber();
 
 	_vp_redraw_regions.clear();
-	DoViewportRedrawRegions(w, left, top, width, height);
+	DoViewportRedrawRegions(w, vp_left, vp_top, vp_width, vp_height);
 
-	if (abs(xo) >= width || abs(yo) >= height) {
+	if (abs(xo) >= vp_width || abs(yo) >= vp_height) {
 		/* fully outside */
 		for (ViewportRedrawRegion &vrr : _vp_redraw_regions) {
 			RedrawScreenRect(vrr.coords.left, vrr.coords.top, vrr.coords.right, vrr.coords.bottom);