diff --git a/src/ai/ai_gui.cpp b/src/ai/ai_gui.cpp
index e100b456c1..a88f56aa02 100644
--- a/src/ai/ai_gui.cpp
+++ b/src/ai/ai_gui.cpp
@@ -239,7 +239,7 @@ static const WindowDesc _ai_list_desc(
 	NULL, _nested_ai_list_widgets, lengthof(_nested_ai_list_widgets)
 );
 
-void ShowAIListWindow(CompanyID slot)
+static void ShowAIListWindow(CompanyID slot)
 {
 	DeleteWindowByClass(WC_AI_LIST);
 	new AIListWindow(&_ai_list_desc, slot);
@@ -438,7 +438,7 @@ static const WindowDesc _ai_settings_desc(
 	NULL, _nested_ai_settings_widgets, lengthof(_nested_ai_settings_widgets)
 );
 
-void ShowAISettingsWindow(CompanyID slot)
+static void ShowAISettingsWindow(CompanyID slot)
 {
 	DeleteWindowByClass(WC_AI_LIST);
 	DeleteWindowByClass(WC_AI_SETTINGS);
diff --git a/src/aystar.cpp b/src/aystar.cpp
index ef8b7657ed..5630c01bbb 100644
--- a/src/aystar.cpp
+++ b/src/aystar.cpp
@@ -90,7 +90,7 @@ static void AyStarMain_OpenList_Add(AyStar *aystar, PathNode *parent, const AySt
  *  return values:
  * AYSTAR_DONE : indicates we are done
  */
-int AyStarMain_CheckTile(AyStar *aystar, AyStarNode *current, OpenListNode *parent)
+static int AyStarMain_CheckTile(AyStar *aystar, AyStarNode *current, OpenListNode *parent)
 {
 	int new_f, new_g, new_h;
 	PathNode *closedlist_parent;
@@ -156,7 +156,7 @@ int AyStarMain_CheckTile(AyStar *aystar, AyStarNode *current, OpenListNode *pare
  *   AYSTAR_FOUND_END_NODE : indicates we found the end. Path_found now is true, and in path is the path found.
  *   AYSTAR_STILL_BUSY : indicates we have done this tile, did not found the path yet, and have items left to try.
  */
-int AyStarMain_Loop(AyStar *aystar)
+static int AyStarMain_Loop(AyStar *aystar)
 {
 	int i, r;
 
@@ -200,7 +200,7 @@ int AyStarMain_Loop(AyStar *aystar)
 /*
  * This function frees the memory it allocated
  */
-void AyStarMain_Free(AyStar *aystar)
+static void AyStarMain_Free(AyStar *aystar)
 {
 	aystar->OpenListQueue.free(&aystar->OpenListQueue, false);
 	/* 2nd argument above is false, below is true, to free the values only
@@ -276,7 +276,7 @@ int AyStarMain_Main(AyStar *aystar)
  * clear() automatically when the algorithm finishes
  * g is the cost for starting with this node.
  */
-void AyStarMain_AddStartNode(AyStar *aystar, AyStarNode *start_node, uint g)
+static void AyStarMain_AddStartNode(AyStar *aystar, AyStarNode *start_node, uint g)
 {
 #ifdef AYSTAR_DEBUG
 	printf("[AyStar] Starting A* Algorithm from node (%d, %d, %d)\n",
diff --git a/src/aystar.h b/src/aystar.h
index 58f0850f94..27170551ab 100644
--- a/src/aystar.h
+++ b/src/aystar.h
@@ -169,11 +169,7 @@ struct AyStar {
 };
 
 
-void AyStarMain_AddStartNode(AyStar *aystar, AyStarNode *start_node, uint g);
 int AyStarMain_Main(AyStar *aystar);
-int AyStarMain_Loop(AyStar *aystar);
-int AyStarMain_CheckTile(AyStar *aystar, AyStarNode *current, OpenListNode *parent);
-void AyStarMain_Free(AyStar *aystar);
 void AyStarMain_Clear(AyStar *aystar);
 
 /* Initialize an AyStar. You should fill all appropriate fields before
diff --git a/src/bridge_map.cpp b/src/bridge_map.cpp
index 2817346efb..80f0f6f180 100644
--- a/src/bridge_map.cpp
+++ b/src/bridge_map.cpp
@@ -14,7 +14,12 @@
 #include "tunnelbridge_map.h"
 
 
-TileIndex GetBridgeEnd(TileIndex tile, DiagDirection dir)
+/**
+ * Finds the end of a bridge in the specified direction starting at a middle tile
+ * @param t the bridge tile to find the bridge ramp for
+ * @param d the direction to search in
+ */
+static TileIndex GetBridgeEnd(TileIndex tile, DiagDirection dir)
 {
 	TileIndexDiff delta = TileOffsByDiagDir(dir);
 
diff --git a/src/bridge_map.h b/src/bridge_map.h
index 1e16fdc063..695b842ade 100644
--- a/src/bridge_map.h
+++ b/src/bridge_map.h
@@ -93,13 +93,6 @@ static inline Axis GetBridgeAxis(TileIndex t)
 	return (Axis)(GB(_m[t].m6, 6, 2) - 1);
 }
 
-/**
- * Finds the end of a bridge in the specified direction starting at a middle tile
- * @param t the bridge tile to find the bridge ramp for
- * @param d the direction to search in
- */
-TileIndex GetBridgeEnd(TileIndex t, DiagDirection d);
-
 /**
  * Finds the northern end of a bridge starting at a middle tile
  * @param t the bridge tile to find the bridge ramp for
diff --git a/src/console.cpp b/src/console.cpp
index f0f97686ab..c8bb2a5644 100644
--- a/src/console.cpp
+++ b/src/console.cpp
@@ -534,6 +534,53 @@ IConsoleVar *IConsoleVarGet(const char *name)
 	return NULL;
 }
 
+/**
+ * Get the value of the variable and put it into a printable
+ * string form so we can use it for printing
+ */
+static char *IConsoleVarGetStringValue(const IConsoleVar *var)
+{
+	static char tempres[50];
+	char *value = tempres;
+
+	switch (var->type) {
+		case ICONSOLE_VAR_BOOLEAN:
+			snprintf(tempres, sizeof(tempres), "%s", (*(bool*)var->addr) ? "on" : "off");
+			break;
+		case ICONSOLE_VAR_BYTE:
+			snprintf(tempres, sizeof(tempres), "%u", *(byte*)var->addr);
+			break;
+		case ICONSOLE_VAR_UINT16:
+			snprintf(tempres, sizeof(tempres), "%u", *(uint16*)var->addr);
+			break;
+		case ICONSOLE_VAR_UINT32:
+			snprintf(tempres, sizeof(tempres), "%u",  *(uint32*)var->addr);
+			break;
+		case ICONSOLE_VAR_INT16:
+			snprintf(tempres, sizeof(tempres), "%i", *(int16*)var->addr);
+			break;
+		case ICONSOLE_VAR_INT32:
+			snprintf(tempres, sizeof(tempres), "%i",  *(int32*)var->addr);
+			break;
+		case ICONSOLE_VAR_STRING:
+			value = (char*)var->addr;
+			break;
+		default: NOT_REACHED();
+	}
+
+	return value;
+}
+
+/**
+ * Print out the value of the variable after it has been assigned
+ * a new value, thus giving us feedback on the action
+ */
+static void IConsoleVarPrintSetValue(const IConsoleVar *var)
+{
+	char *value = IConsoleVarGetStringValue(var);
+	IConsolePrintF(CC_WARNING, "'%s' changed to:  %s", var->name, value);
+}
+
 /**
  * Set a new value to a console variable
  * @param *var the variable being set/changed
@@ -618,43 +665,6 @@ static uint32 IConsoleVarGetValue(const IConsoleVar *var)
 	return result;
 }
 
-/**
- * Get the value of the variable and put it into a printable
- * string form so we can use it for printing
- */
-static char *IConsoleVarGetStringValue(const IConsoleVar *var)
-{
-	static char tempres[50];
-	char *value = tempres;
-
-	switch (var->type) {
-		case ICONSOLE_VAR_BOOLEAN:
-			snprintf(tempres, sizeof(tempres), "%s", (*(bool*)var->addr) ? "on" : "off");
-			break;
-		case ICONSOLE_VAR_BYTE:
-			snprintf(tempres, sizeof(tempres), "%u", *(byte*)var->addr);
-			break;
-		case ICONSOLE_VAR_UINT16:
-			snprintf(tempres, sizeof(tempres), "%u", *(uint16*)var->addr);
-			break;
-		case ICONSOLE_VAR_UINT32:
-			snprintf(tempres, sizeof(tempres), "%u",  *(uint32*)var->addr);
-			break;
-		case ICONSOLE_VAR_INT16:
-			snprintf(tempres, sizeof(tempres), "%i", *(int16*)var->addr);
-			break;
-		case ICONSOLE_VAR_INT32:
-			snprintf(tempres, sizeof(tempres), "%i",  *(int32*)var->addr);
-			break;
-		case ICONSOLE_VAR_STRING:
-			value = (char*)var->addr;
-			break;
-		default: NOT_REACHED();
-	}
-
-	return value;
-}
-
 /**
  * Print out the value of the variable when asked
  */
@@ -672,16 +682,6 @@ void IConsoleVarPrintGetValue(const IConsoleVar *var)
 	IConsolePrintF(CC_WARNING, "Current value for '%s' is:  %s", var->name, value);
 }
 
-/**
- * Print out the value of the variable after it has been assigned
- * a new value, thus giving us feedback on the action
- */
-void IConsoleVarPrintSetValue(const IConsoleVar *var)
-{
-	char *value = IConsoleVarGetStringValue(var);
-	IConsolePrintF(CC_WARNING, "'%s' changed to:  %s", var->name, value);
-}
-
 /**
  * Execute a variable command. Without any parameters, print out its value
  * with parameters it assigns a new value to the variable
@@ -689,7 +689,7 @@ void IConsoleVarPrintSetValue(const IConsoleVar *var)
  * @param tokencount how many additional parameters have been given to the commandline
  * @param *token the actual parameters the variable was called with
  */
-void IConsoleVarExec(const IConsoleVar *var, byte tokencount, char *token[ICON_TOKEN_COUNT])
+static void IConsoleVarExec(const IConsoleVar *var, byte tokencount, char *token[ICON_TOKEN_COUNT])
 {
 	const char *tokenptr = token[0];
 	byte t_index = tokencount;
diff --git a/src/console_gui.cpp b/src/console_gui.cpp
index 2486f7588a..4c0a2c1761 100644
--- a/src/console_gui.cpp
+++ b/src/console_gui.cpp
@@ -407,7 +407,6 @@ void IConsoleSwitch()
 }
 
 void IConsoleClose() {if (_iconsole_mode == ICONSOLE_OPENED) IConsoleSwitch();}
-void IConsoleOpen()  {if (_iconsole_mode == ICONSOLE_CLOSED) IConsoleSwitch();}
 
 /**
  * Add the entered line into the history so you can look it back
diff --git a/src/console_internal.h b/src/console_internal.h
index 72e8ab57ec..f36ee39508 100644
--- a/src/console_internal.h
+++ b/src/console_internal.h
@@ -110,7 +110,6 @@ extern IConsoleAlias *_iconsole_aliases; ///< list of registred aliases
 
 /* console functions */
 void IConsoleClearBuffer();
-void IConsoleOpen();
 
 /* Commands */
 void IConsoleCmdRegister(const char *name, IConsoleCmdProc *proc);
@@ -123,10 +122,6 @@ void IConsoleVarRegister(const char *name, void *addr, IConsoleVarTypes type, co
 void IConsoleVarStringRegister(const char *name, void *addr, uint32 size, const char *help);
 IConsoleVar *IConsoleVarGet(const char *name);
 void IConsoleVarPrintGetValue(const IConsoleVar *var);
-void IConsoleVarPrintSetValue(const IConsoleVar *var);
-
-/* Parser */
-void IConsoleVarExec(const IConsoleVar *var, byte tokencount, char *token[]);
 
 /* console std lib (register ingame commands/aliases/variables) */
 void IConsoleStdLibRegister();
diff --git a/src/fileio.cpp b/src/fileio.cpp
index 45d88b82ca..858ac5abba 100644
--- a/src/fileio.cpp
+++ b/src/fileio.cpp
@@ -302,7 +302,7 @@ char *FioGetDirectory(char *buf, size_t buflen, Subdirectory subdir)
 	return buf;
 }
 
-FILE *FioFOpenFileSp(const char *filename, const char *mode, Searchpath sp, Subdirectory subdir, size_t *filesize)
+static FILE *FioFOpenFileSp(const char *filename, const char *mode, Searchpath sp, Subdirectory subdir, size_t *filesize)
 {
 #if defined(WIN32) && defined(UNICODE)
 	/* fopen is implemented as a define with ellipses for
@@ -436,7 +436,7 @@ void FioCreateDirectory(const char *name)
  * @param buf    string to append the separator to
  * @param buflen the length of the buf
  */
-void AppendPathSeparator(char *buf, size_t buflen)
+static void AppendPathSeparator(char *buf, size_t buflen)
 {
 	size_t s = strlen(buf);
 
diff --git a/src/fileio_func.h b/src/fileio_func.h
index b2d2da8032..4b42e4908a 100644
--- a/src/fileio_func.h
+++ b/src/fileio_func.h
@@ -57,7 +57,6 @@ char *FioAppendDirectory(char *buf, size_t buflen, Searchpath sp, Subdirectory s
 char *FioGetDirectory(char *buf, size_t buflen, Subdirectory subdir);
 
 void SanitizeFilename(char *filename);
-void AppendPathSeparator(char *buf, size_t buflen);
 void DeterminePaths(const char *exe);
 void *ReadFileToMem(const char *filename, size_t *lenp, size_t maxsize);
 bool FileExists(const char *filename);
diff --git a/src/fontcache.cpp b/src/fontcache.cpp
index 7ccdfb9311..43852fa291 100644
--- a/src/fontcache.cpp
+++ b/src/fontcache.cpp
@@ -902,7 +902,7 @@ static void SetGlyphPtr(FontSize size, WChar key, const GlyphEntry *glyph)
 	_glyph_ptr[size][GB(key, 8, 8)][GB(key, 0, 8)].width  = glyph->width;
 }
 
-void *AllocateFont(size_t size)
+static void *AllocateFont(size_t size)
 {
 	return MallocT<byte>(size);
 }
diff --git a/src/genworld_gui.cpp b/src/genworld_gui.cpp
index 941e7bfec5..d89f134fdb 100644
--- a/src/genworld_gui.cpp
+++ b/src/genworld_gui.cpp
@@ -310,7 +310,7 @@ static const NWidgetPart _nested_heightmap_load_widgets[] = {
 	EndContainer(),
 };
 
-void StartGeneratingLandscape(glwp_modes mode)
+static void StartGeneratingLandscape(glwp_modes mode)
 {
 	DeleteAllNonVitalWindows();
 
diff --git a/src/gfxinit.cpp b/src/gfxinit.cpp
index 70e01886b9..686951a75a 100644
--- a/src/gfxinit.cpp
+++ b/src/gfxinit.cpp
@@ -65,7 +65,7 @@ static uint LoadGrfFile(const char *filename, uint load_index, int file_index)
 }
 
 
-void LoadSpritesIndexed(int file_index, uint *sprite_id, const SpriteID *index_tbl)
+static void LoadSpritesIndexed(int file_index, uint *sprite_id, const SpriteID *index_tbl)
 {
 	uint start;
 	while ((start = *index_tbl++) != END) {
diff --git a/src/gfxinit.h b/src/gfxinit.h
index 26c662b3d4..5bf0bff5ca 100644
--- a/src/gfxinit.h
+++ b/src/gfxinit.h
@@ -12,9 +12,6 @@
 #ifndef GFXINIT_H
 #define GFXINIT_H
 
-#include "gfx_type.h"
-
 void GfxLoadSprites();
-void LoadSpritesIndexed(int file_index, uint *sprite_id, const SpriteID *index_tbl);
 
 #endif /* GFXINIT_H */
diff --git a/src/industry_cmd.cpp b/src/industry_cmd.cpp
index 42b66ca12c..7080ac4a8e 100644
--- a/src/industry_cmd.cpp
+++ b/src/industry_cmd.cpp
@@ -2058,7 +2058,7 @@ static void CanCargoServiceIndustry(CargoID cargo, Industry *ind, bool *c_accept
  * service the industry, and 1 otherwise (only competitors can service the
  * industry)
  */
-int WhoCanServiceIndustry(Industry *ind)
+static int WhoCanServiceIndustry(Industry *ind)
 {
 	/* Find all stations within reach of the industry */
 	StationList stations;
diff --git a/src/network/network_udp.cpp b/src/network/network_udp.cpp
index acf1afb2d3..b9d812ede9 100644
--- a/src/network/network_udp.cpp
+++ b/src/network/network_udp.cpp
@@ -430,7 +430,7 @@ struct NetworkUDPQueryServerInfo : NetworkAddress {
  * Threaded part for resolving the IP of a server and querying it.
  * @param pntr the NetworkUDPQueryServerInfo.
  */
-void NetworkUDPQueryServerThread(void *pntr)
+static void NetworkUDPQueryServerThread(void *pntr)
 {
 	NetworkUDPQueryServerInfo *info = (NetworkUDPQueryServerInfo*)pntr;
 
@@ -459,7 +459,7 @@ void NetworkUDPQueryServer(NetworkAddress address, bool manually)
 	}
 }
 
-void NetworkUDPRemoveAdvertiseThread(void *pntr)
+static void NetworkUDPRemoveAdvertiseThread(void *pntr)
 {
 	DEBUG(net, 1, "[udp] removing advertise from master server");
 
@@ -491,7 +491,7 @@ void NetworkUDPRemoveAdvertise(bool blocking)
 	}
 }
 
-void NetworkUDPAdvertiseThread(void *pntr)
+static void NetworkUDPAdvertiseThread(void *pntr)
 {
 	/* Find somewhere to send */
 	NetworkAddress out_addr(NETWORK_MASTER_SERVER_HOST, NETWORK_MASTER_SERVER_PORT);
diff --git a/src/news_gui.cpp b/src/news_gui.cpp
index 5686102f17..84eb246659 100644
--- a/src/news_gui.cpp
+++ b/src/news_gui.cpp
@@ -775,7 +775,7 @@ void DeleteIndustryNews(IndustryID iid)
 	}
 }
 
-void RemoveOldNewsItems()
+static void RemoveOldNewsItems()
 {
 	NewsItem *next;
 	for (NewsItem *cur = _oldest_news; _total_news > MIN_NEWS_AMOUNT && cur != NULL; cur = next) {
diff --git a/src/os/unix/crashlog_unix.cpp b/src/os/unix/crashlog_unix.cpp
index 0c2690610d..ed7f2127f9 100644
--- a/src/os/unix/crashlog_unix.cpp
+++ b/src/os/unix/crashlog_unix.cpp
@@ -143,7 +143,7 @@ static const int _signals_to_handle[] = { SIGSEGV, SIGABRT, SIGFPE, SIGBUS };
  * @note Not static so it shows up in the backtrace.
  * @param signum the signal that caused us to crash.
  */
-void CDECL HandleCrash(int signum)
+static void CDECL HandleCrash(int signum)
 {
 	/* Disable all handling of signals by us, so we don't go into infinite loops. */
 	for (const int *i = _signals_to_handle; i != endof(_signals_to_handle); i++) {
diff --git a/src/rail.h b/src/rail.h
index ae19c97c19..06445d5581 100644
--- a/src/rail.h
+++ b/src/rail.h
@@ -227,7 +227,6 @@ static inline Money RailConvertCost(RailType from, RailType to)
 	return RailBuildCost(to) + _price[PR_CLEAR_RAIL];
 }
 
-Vehicle *UpdateTrainPowerProc(Vehicle *v, void *data);
 void DrawTrainDepotSprite(int x, int y, int image, RailType railtype);
 Vehicle *EnsureNoTrainOnTrackProc(Vehicle *v, void *data);
 int TicksToLeaveDepot(const Train *v);
diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
index eca108f021..855ee1afa5 100644
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -1256,7 +1256,7 @@ CommandCost CmdRemoveSignalTrack(TileIndex tile, DoCommandFlag flags, uint32 p1,
 }
 
 /** Update power of train under which is the railtype being converted */
-Vehicle *UpdateTrainPowerProc(Vehicle *v, void *data)
+static Vehicle *UpdateTrainPowerProc(Vehicle *v, void *data)
 {
 	if (v->type != VEH_TRAIN) return NULL;
 
diff --git a/src/road.cpp b/src/road.cpp
index 5e802f786a..705270186a 100644
--- a/src/road.cpp
+++ b/src/road.cpp
@@ -21,7 +21,14 @@
 #include "date_func.h"
 #include "landscape.h"
 
-bool IsPossibleCrossing(const TileIndex tile, Axis ax)
+/**
+ * Return if the tile is a valid tile for a crossing.
+ *
+ * @param tile the curent tile
+ * @param ax the axis of the road over the rail
+ * @return true if it is a valid tile
+ */
+static bool IsPossibleCrossing(const TileIndex tile, Axis ax)
 {
 	return (IsTileType(tile, MP_RAILWAY) &&
 		GetRailTileType(tile) == RAIL_TILE_NORMAL &&
diff --git a/src/road_cmd.cpp b/src/road_cmd.cpp
index ff610554fa..9b59155898 100644
--- a/src/road_cmd.cpp
+++ b/src/road_cmd.cpp
@@ -103,7 +103,7 @@ static const RoadBits _invalid_tileh_slopes_road[2][15] = {
 	}
 };
 
-Foundation GetRoadFoundation(Slope tileh, RoadBits bits);
+static Foundation GetRoadFoundation(Slope tileh, RoadBits bits);
 
 /**
  * Is it allowed to remove the given road bits from the given tile?
@@ -981,7 +981,7 @@ struct DrawRoadTileStruct {
  * @param bits The RoadBits part
  * @return The resulting Foundation
  */
-Foundation GetRoadFoundation(Slope tileh, RoadBits bits)
+static Foundation GetRoadFoundation(Slope tileh, RoadBits bits)
 {
 	/* Flat land and land without a road doesn't require a foundation */
 	if (tileh == SLOPE_FLAT || bits == ROAD_NONE) return FOUNDATION_NONE;
diff --git a/src/road_map.h b/src/road_map.h
index d5f98ff498..bea758e2cc 100644
--- a/src/road_map.h
+++ b/src/road_map.h
@@ -369,16 +369,6 @@ static inline DiagDirection GetRoadDepotDirection(TileIndex t)
  */
 RoadBits GetAnyRoadBits(TileIndex tile, RoadType rt, bool straight_tunnel_bridge_entrance = false);
 
-/**
- * Return if the tile is a valid tile for a crossing.
- *
- * @note function is overloaded
- * @param tile the curent tile
- * @param ax the axis of the road over the rail
- * @return true if it is a valid tile
- */
-bool IsPossibleCrossing(const TileIndex tile, Axis ax);
-
 
 static inline void MakeRoadNormal(TileIndex t, RoadBits bits, RoadTypes rot, TownID town, Owner road, Owner tram)
 {
diff --git a/src/saveload/oldloader_sl.cpp b/src/saveload/oldloader_sl.cpp
index 332447b6c4..7acac29379 100644
--- a/src/saveload/oldloader_sl.cpp
+++ b/src/saveload/oldloader_sl.cpp
@@ -148,7 +148,7 @@ static uint32 RemapOldTownName(uint32 townnameparts, byte old_town_name_type)
 
 #undef FIXNUM
 
-void FixOldTowns()
+static void FixOldTowns()
 {
 	Town *town;
 
diff --git a/src/saveload/saveload.cpp b/src/saveload/saveload.cpp
index 3eb4ae6f5d..76025aee77 100644
--- a/src/saveload/saveload.cpp
+++ b/src/saveload/saveload.cpp
@@ -767,7 +767,7 @@ static inline size_t SlCalcListLen(const void *list)
  * @param list The list being manipulated
  * @param conv SLRefType type of the list (Vehicle *, Station *, etc)
  */
-void SlList(void *list, SLRefType conv)
+static void SlList(void *list, SLRefType conv)
 {
 	/* Automatically calculate the length? */
 	if (_sl.need_length != NL_NONE) {
diff --git a/src/saveload/station_sl.cpp b/src/saveload/station_sl.cpp
index 9c44ddb264..1e0f6d8875 100644
--- a/src/saveload/station_sl.cpp
+++ b/src/saveload/station_sl.cpp
@@ -259,7 +259,7 @@ static void Load_STNS()
 	}
 }
 
-void Ptrs_STNS()
+static void Ptrs_STNS()
 {
 	/* Don't run when savegame version is higher than or equal to 123. */
 	if (!CheckSavegameVersion(123)) return;
diff --git a/src/saveload/subsidy_sl.cpp b/src/saveload/subsidy_sl.cpp
index 62f31ab196..e5c18a2a41 100644
--- a/src/saveload/subsidy_sl.cpp
+++ b/src/saveload/subsidy_sl.cpp
@@ -27,7 +27,7 @@ static const SaveLoad _subsidies_desc[] = {
 	SLE_END()
 };
 
-void Save_SUBS()
+static void Save_SUBS()
 {
 	Subsidy *s;
 	FOR_ALL_SUBSIDIES(s) {
@@ -36,7 +36,7 @@ void Save_SUBS()
 	}
 }
 
-void Load_SUBS()
+static void Load_SUBS()
 {
 	int index;
 	while ((index = SlIterateArray()) != -1) {
diff --git a/src/saveload/vehicle_sl.cpp b/src/saveload/vehicle_sl.cpp
index f0cc170caa..0e1023909d 100644
--- a/src/saveload/vehicle_sl.cpp
+++ b/src/saveload/vehicle_sl.cpp
@@ -737,7 +737,7 @@ void Load_VEHS()
 	}
 }
 
-void Ptrs_VEHS()
+static void Ptrs_VEHS()
 {
 	Vehicle *v;
 	FOR_ALL_VEHICLES(v) {
diff --git a/src/settings.cpp b/src/settings.cpp
index 25f95645c5..2ea624c331 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -796,7 +796,7 @@ void SetDifficultyLevel(int mode, DifficultySettings *gm_opt)
  * Checks the difficulty levels read from the configuration and
  * forces them to be correct when invalid.
  */
-void CheckDifficultyLevels()
+static void CheckDifficultyLevels()
 {
 	if (_settings_newgame.difficulty.diff_level != 3) {
 		SetDifficultyLevel(_settings_newgame.difficulty.diff_level, &_settings_newgame.difficulty);
@@ -1048,7 +1048,7 @@ static void HandleOldDiffCustom(bool savegame)
  * @param name pointer to the string defining name of the old news config
  * @param value pointer to the string defining value of the old news config
  * @returns true if conversion could have been made */
-bool ConvertOldNewsSetting(const char *name, const char *value)
+static bool ConvertOldNewsSetting(const char *name, const char *value)
 {
 	if (strcasecmp(name, "openclose") == 0) {
 		/* openclose has been split in "open" and "close".
diff --git a/src/settings_gui.cpp b/src/settings_gui.cpp
index 5611f27a57..ad77dd6a0b 100644
--- a/src/settings_gui.cpp
+++ b/src/settings_gui.cpp
@@ -1052,7 +1052,7 @@ uint SettingEntry::Draw(GameSettings *settings_ptr, int base_x, int base_y, int
 	return cur_row;
 }
 
-const void *ResolveVariableAddress(const GameSettings *settings_ptr, const SettingDesc *sd)
+static const void *ResolveVariableAddress(const GameSettings *settings_ptr, const SettingDesc *sd)
 {
 	if ((sd->desc.flags & SGF_PER_COMPANY) != 0) {
 		if (Company::IsValidID(_local_company) && _game_mode != GM_MENU) {
diff --git a/src/spritecache.cpp b/src/spritecache.cpp
index b7104290e3..2cf4eff2b9 100644
--- a/src/spritecache.cpp
+++ b/src/spritecache.cpp
@@ -141,7 +141,7 @@ bool SpriteExists(SpriteID id)
 	return !(GetSpriteCache(id)->file_pos == 0 && GetSpriteCache(id)->file_slot == 0);
 }
 
-void *AllocSprite(size_t);
+static void *AllocSprite(size_t);
 
 static void *ReadSprite(SpriteCache *sc, SpriteID id, SpriteType sprite_type)
 {
@@ -451,7 +451,7 @@ static void DeleteEntryFromSpriteCache()
 	}
 }
 
-void *AllocSprite(size_t mem_req)
+static void *AllocSprite(size_t mem_req)
 {
 	mem_req += sizeof(MemBlock);
 
diff --git a/src/station_cmd.cpp b/src/station_cmd.cpp
index 3e12f6d5f4..58ffc5ef30 100644
--- a/src/station_cmd.cpp
+++ b/src/station_cmd.cpp
@@ -917,7 +917,7 @@ CommandCost FindJoiningBaseStation(StationID existing_station, StationID station
  * @param st 'return' pointer for the found station
  * @return command cost with the error or 'okay'
  */
-CommandCost FindJoiningStation(StationID existing_station, StationID station_to_join, bool adjacent, TileArea ta, Station **st)
+static CommandCost FindJoiningStation(StationID existing_station, StationID station_to_join, bool adjacent, TileArea ta, Station **st)
 {
 	return FindJoiningBaseStation<Station, STR_ERROR_MUST_REMOVE_RAILWAY_STATION_FIRST>(existing_station, station_to_join, adjacent, ta, st);
 }
diff --git a/src/vehicle_gui.cpp b/src/vehicle_gui.cpp
index e4587895f2..fea1ab403d 100644
--- a/src/vehicle_gui.cpp
+++ b/src/vehicle_gui.cpp
@@ -122,7 +122,7 @@ void DepotSortList(VehicleList *list)
 }
 
 /** draw the vehicle profit button in the vehicle list window. */
-void DrawVehicleProfitButton(const Vehicle *v, int x, int y)
+static void DrawVehicleProfitButton(const Vehicle *v, int x, int y)
 {
 	SpriteID pal;
 
diff --git a/src/vehicle_gui.h b/src/vehicle_gui.h
index 75705ec594..649025ba3e 100644
--- a/src/vehicle_gui.h
+++ b/src/vehicle_gui.h
@@ -19,7 +19,6 @@
 #include "engine_type.h"
 #include "tile_type.h"
 
-void DrawVehicleProfitButton(const Vehicle *v, int x, int y);
 void ShowVehicleRefitWindow(const Vehicle *v, VehicleOrderID order, Window *parent);
 
 /** Constants of vehicle view widget indices */
diff --git a/src/waypoint_cmd.cpp b/src/waypoint_cmd.cpp
index bab3eb4ac7..9d13663605 100644
--- a/src/waypoint_cmd.cpp
+++ b/src/waypoint_cmd.cpp
@@ -46,7 +46,7 @@ void Waypoint::UpdateVirtCoord()
  * Set the default name for a waypoint
  * @param wp Waypoint to work on
  */
-void MakeDefaultWaypointName(Waypoint *wp)
+static void MakeDefaultWaypointName(Waypoint *wp)
 {
 	uint32 used = 0; // bitmap of used waypoint numbers, sliding window with 'next' as base
 	uint32 next = 0; // first waypoint number in the bitmap
diff --git a/src/waypoint_func.h b/src/waypoint_func.h
index 6c6d799055..d2f22da236 100644
--- a/src/waypoint_func.h
+++ b/src/waypoint_func.h
@@ -22,6 +22,5 @@ CommandCost RemoveBuoy(TileIndex tile, DoCommandFlag flags);
 Axis GetAxisForNewWaypoint(TileIndex tile);
 void ShowWaypointWindow(const Waypoint *wp);
 void DrawWaypointSprite(int x, int y, int stat_id, RailType railtype);
-void MakeDefaultWaypointName(Waypoint *wp);
 
 #endif /* WAYPOINT_FUNC_H */
diff --git a/src/widget.cpp b/src/widget.cpp
index aabd1c5734..126dcd3f24 100644
--- a/src/widget.cpp
+++ b/src/widget.cpp
@@ -2314,7 +2314,7 @@ bool NWidgetLeaf::ButtonHit(const Point &pt)
  * @note Caller should release returned widget array with \c free(widgets).
  * @ingroup NestedWidgets
  */
-Widget *InitializeNWidgets(NWidgetBase *nwid, bool rtl, int biggest_index)
+static Widget *InitializeNWidgets(NWidgetBase *nwid, bool rtl, int biggest_index)
 {
 	/* Initialize nested widgets. */
 	nwid->SetupSmallestSize(NULL, false);
diff --git a/src/widget_type.h b/src/widget_type.h
index dab4fad327..f85c2ec3ac 100644
--- a/src/widget_type.h
+++ b/src/widget_type.h
@@ -548,7 +548,6 @@ private:
 	static Dimension closebox_dimension;  ///< Cached size of a closebox widget.
 };
 
-Widget *InitializeNWidgets(NWidgetBase *nwid, bool rtl = false);
 bool CompareWidgetArrays(const Widget *orig, const Widget *gen, bool report = true);
 
 /**