diff --git a/src/company_gui.cpp b/src/company_gui.cpp
--- a/src/company_gui.cpp
+++ b/src/company_gui.cpp
@@ -636,7 +636,7 @@ private:
 		const Company *c;
 		const Livery *livery, *default_livery = nullptr;
 		bool primary = widget == WID_SCL_PRI_COL_DROPDOWN;
-		byte default_col;
+		byte default_col = 0;
 
 		/* Disallow other company colours for the primary colour */
 		if (this->livery_class < LC_GROUP_RAIL && HasBit(this->sel, LS_DEFAULT) && primary) {
diff --git a/src/script/api/script_rail.cpp b/src/script/api/script_rail.cpp
--- a/src/script/api/script_rail.cpp
+++ b/src/script/api/script_rail.cpp
@@ -449,7 +449,7 @@ static bool IsValidSignalType(int signal
 	EnforcePrecondition(false, ::IsValidSignalType(signal));
 
 	Track track = INVALID_TRACK;
-	uint signal_cycles;
+	uint signal_cycles = 0;
 
 	int data_index = 2 + (::TileX(front) - ::TileX(tile)) + 2 * (::TileY(front) - ::TileY(tile));
 	for (int i = 0; i < NUM_TRACK_DIRECTIONS; i++) {