diff --git a/src/pathfinder/yapf/yapf_costrail.hpp b/src/pathfinder/yapf/yapf_costrail.hpp
index 2169429131..8a78208d5d 100644
--- a/src/pathfinder/yapf/yapf_costrail.hpp
+++ b/src/pathfinder/yapf/yapf_costrail.hpp
@@ -70,8 +70,8 @@ protected:
 		int p1 = Yapf().PfGetSettings().rail_look_ahead_signal_p1;
 		int p2 = Yapf().PfGetSettings().rail_look_ahead_signal_p2;
 		int *pen = m_sig_look_ahead_costs.GrowSizeNC(Yapf().PfGetSettings().rail_look_ahead_max_signals);
-		for (uint i = 0; i < Yapf().PfGetSettings().rail_look_ahead_max_signals; i++) {
-			pen[i] = p0 + i * (p1 + i * p2);
+		for (int i = 0; i < (int) Yapf().PfGetSettings().rail_look_ahead_max_signals; i++) {
+			pen[i] = max<int>(0, p0 + i * (p1 + i * p2));
 		}
 	}
 
diff --git a/src/pathfinder/yapf/yapf_rail.cpp b/src/pathfinder/yapf/yapf_rail.cpp
index e4d5085b92..60b163e958 100644
--- a/src/pathfinder/yapf/yapf_rail.cpp
+++ b/src/pathfinder/yapf/yapf_rail.cpp
@@ -17,6 +17,7 @@
 #include "../../viewport_func.h"
 #include "../../newgrf_station.h"
 #include "../../tracerestrict.h"
+#include "../../debug.h"
 
 #include "../../safeguards.h"
 
@@ -762,3 +763,18 @@ void YapfNotifyTrackLayoutChange(TileIndex tile, Track track)
 {
 	CSegmentCostCacheBase::NotifyTrackLayoutChange(tile, track);
 }
+
+void YapfCheckRailSignalPenalties()
+{
+	bool negative = false;
+	int p0 = _settings_game.pf.yapf.rail_look_ahead_signal_p0;
+	int p1 = _settings_game.pf.yapf.rail_look_ahead_signal_p1;
+	int p2 = _settings_game.pf.yapf.rail_look_ahead_signal_p2;
+	for (int i = 0; i < (int) _settings_game.pf.yapf.rail_look_ahead_max_signals; i++) {
+		if (p0 + i * (p1 + i * p2) < 0) negative = true;
+	}
+	if (negative) {
+		DEBUG(misc, 0, "Settings: pf.yapf.rail_look_ahead_signal_p0, pf.yapf.rail_look_ahead_signal_p1, pf.yapf.rail_look_ahead_signal_p2 and pf.yapf.rail_look_ahead_max_signal "
+				"are set to incorrect values (i.e. resulting in hegative penalties), negative penalties will be truncated");
+	}
+}
diff --git a/src/saveload/afterload.cpp b/src/saveload/afterload.cpp
index b51f6af1ec..01b6d1c345 100644
--- a/src/saveload/afterload.cpp
+++ b/src/saveload/afterload.cpp
@@ -3795,6 +3795,9 @@ bool AfterLoadGame()
 	InvalidateVehicleTickCaches();
 	ClearVehicleTickCaches();
 
+	extern void YapfCheckRailSignalPenalties();
+	YapfCheckRailSignalPenalties();
+
 	/* Show this message last to avoid covering up an error message if we bail out part way */
 	switch (gcf_res) {
 		case GLC_COMPATIBLE: ShowErrorMessage(STR_NEWGRF_COMPATIBLE_LOAD_WARNING, INVALID_STRING_ID, WL_CRITICAL); break;
diff --git a/src/settings.cpp b/src/settings.cpp
index ec02a42819..d587585d26 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -1228,6 +1228,14 @@ static bool EnableSingleVehSharedOrderGuiChanged(int32)
 	return true;
 }
 
+static bool CheckYapfRailSignalPenalties(int32)
+{
+	extern void YapfCheckRailSignalPenalties();
+	YapfCheckRailSignalPenalties();
+
+	return true;
+}
+
 /** Checks if any settings are set to incorrect values, and sets them to correct values in that case. */
 static void ValidateSettings()
 {
diff --git a/src/table/settings.ini b/src/table/settings.ini
index 05310f0f09..4a0f3911cb 100644
--- a/src/table/settings.ini
+++ b/src/table/settings.ini
@@ -47,6 +47,7 @@ static bool ImprovedBreakdownsSettingChanged(int32 p1);
 static bool DayLengthChanged(int32 p1);
 static bool SimulatedWormholeSignalsChanged(int32 p1);
 static bool EnableSingleVehSharedOrderGuiChanged(int32 p1);
+static bool CheckYapfRailSignalPenalties(int32 p1);
 
 static bool UpdateClientName(int32 p1);
 static bool UpdateServerPassword(int32 p1);
@@ -3078,6 +3079,7 @@ def      = 10
 min      = 1
 max      = 100
 cat      = SC_EXPERT
+proc     = CheckYapfRailSignalPenalties
 
 [SDT_VAR]
 base     = GameSettings
@@ -3088,6 +3090,7 @@ def      = 500
 min      = -1000000
 max      = 1000000
 cat      = SC_EXPERT
+proc     = CheckYapfRailSignalPenalties
 
 [SDT_VAR]
 base     = GameSettings
@@ -3098,6 +3101,7 @@ def      = -100
 min      = -1000000
 max      = 1000000
 cat      = SC_EXPERT
+proc     = CheckYapfRailSignalPenalties
 
 [SDT_VAR]
 base     = GameSettings
@@ -3108,6 +3112,7 @@ def      = 5
 min      = -1000000
 max      = 1000000
 cat      = SC_EXPERT
+proc     = CheckYapfRailSignalPenalties
 
 [SDT_VAR]
 base     = GameSettings