diff --git a/src/command.cpp b/src/command.cpp
index 169c2b6d0e..ab5d29764c 100644
--- a/src/command.cpp
+++ b/src/command.cpp
@@ -591,7 +591,7 @@ CommandCost DoCommandPInternal(TileIndex tile, uint32 p1, uint32 p2, uint32 cmd,
 	if (tile != 0 && (tile >= MapSize() || (!IsValidTile(tile) && (cmd_flags & CMD_ALL_TILES) == 0))) return_dcpi(CMD_ERROR, false);
 
 	/* Always execute server and spectator commands as spectator */
-	bool exec_as_spectator = cmd_flags & (CMD_SPECTATOR | CMD_SERVER);
+	bool exec_as_spectator = (cmd_flags & (CMD_SPECTATOR | CMD_SERVER)) != 0;
 
 	/* If the company isn't valid it may only do server command or start a new company!
 	 * The server will ditch any server commands a client sends to it, so effectively
diff --git a/src/newgrf_debug_gui.cpp b/src/newgrf_debug_gui.cpp
index 703edf9053..019bd20b97 100644
--- a/src/newgrf_debug_gui.cpp
+++ b/src/newgrf_debug_gui.cpp
@@ -104,6 +104,9 @@ struct NIVariable {
 /** Helper class to wrap some functionality/queries in. */
 class NIHelper {
 public:
+	/** Silence a warning. */
+	virtual ~NIHelper() {}
+
 	/**
 	 * Is the item with the given index inspectable?
 	 * @param index the index to check.
diff --git a/src/saveload/afterload.cpp b/src/saveload/afterload.cpp
index 467e24fa2a..dd25705ab1 100644
--- a/src/saveload/afterload.cpp
+++ b/src/saveload/afterload.cpp
@@ -431,7 +431,6 @@ bool AfterLoadGame()
 	SetSignalHandlers();
 
 	TileIndex map_size = MapSize();
-	Company *c;
 
 	if (CheckSavegameVersion(98)) GamelogOldver();
 
@@ -500,6 +499,7 @@ bool AfterLoadGame()
 	}
 
 	if (CheckSavegameVersion(84)) {
+		Company *c;
 		FOR_ALL_COMPANIES(c) {
 			c->name = CopyFromOldName(c->name_1);
 			if (c->name != NULL) c->name_1 = STR_SV_UNNAMED;
@@ -803,6 +803,7 @@ bool AfterLoadGame()
 	/* From version 16.0, we included autorenew on engines, which are now saved, but
 	 *  of course, we do need to initialize them for older savegames. */
 	if (CheckSavegameVersion(16)) {
+		Company *c;
 		FOR_ALL_COMPANIES(c) {
 			c->engine_renew_list            = NULL;
 			c->settings.engine_renew        = false;
@@ -1089,6 +1090,7 @@ bool AfterLoadGame()
 	 * replaced, shall keep their old length. In all prior versions, just default
 	 * to false */
 	if (CheckSavegameVersionOldStyle(16, 1)) {
+		Company *c;
 		FOR_ALL_COMPANIES(c) c->settings.renew_keep_length = false;
 	}
 
@@ -1147,8 +1149,12 @@ bool AfterLoadGame()
 
 	YapfNotifyTrackLayoutChange(INVALID_TILE, INVALID_TRACK);
 
-	if (CheckSavegameVersion(34)) FOR_ALL_COMPANIES(c) ResetCompanyLivery(c);
+	if (CheckSavegameVersion(34)) {
+		Company *c;
+		FOR_ALL_COMPANIES(c) ResetCompanyLivery(c);
+	}
 
+	Company *c;
 	FOR_ALL_COMPANIES(c) {
 		c->avail_railtypes = GetCompanyRailtypes(c->index);
 		c->avail_roadtypes = GetCompanyRoadtypes(c->index);
diff --git a/src/train_gui.cpp b/src/train_gui.cpp
index 30f0792062..35bd1d266a 100644
--- a/src/train_gui.cpp
+++ b/src/train_gui.cpp
@@ -55,7 +55,7 @@ void CcBuildWagon(const CommandCost &result, TileIndex tile, uint32 p1, uint32 p
  * @param selection Selected vehicle that is dragged.
  * @return The width of the highlight mark.
  */
-static uint HighlightDragPosition(int px, int max_width, VehicleID selection)
+static int HighlightDragPosition(int px, int max_width, VehicleID selection)
 {
 	bool rtl = _dynlang.text_dir == TD_RTL;
 
@@ -108,7 +108,7 @@ void DrawTrainImage(const Train *v, int left, int right, int y, VehicleID select
 	for (; v != NULL && (rtl ? px > 0 : px < max_width); v = v->Next()) {
 		if (dragging && !drag_at_end_of_train && drag_dest == v->index) {
 			/* Highlight the drag-and-drop destination inside the train. */
-			uint drag_hlight_width = HighlightDragPosition(px, max_width, selection);
+			int drag_hlight_width = HighlightDragPosition(px, max_width, selection);
 			px += rtl ? -drag_hlight_width : drag_hlight_width;
 		}