diff --git a/src/industry_gui.cpp b/src/industry_gui.cpp
index d083ce261b..0b0693e8e4 100644
--- a/src/industry_gui.cpp
+++ b/src/industry_gui.cpp
@@ -375,7 +375,7 @@ class BuildIndustryWindow : public Window {
 
 		std::string cargostring;
 		size_t numcargo = 0;
-		size_t firstcargo;
+		size_t firstcargo = 0;
 
 		for (size_t j = 0; j < cargolist.size(); j++) {
 			if (!IsValidCargoID(cargolist[j])) continue;
diff --git a/src/newgrf_class.h b/src/newgrf_class.h
index e04c86adac..e206ad0004 100644
--- a/src/newgrf_class.h
+++ b/src/newgrf_class.h
@@ -29,7 +29,7 @@ private:
 	static_assert(std::is_base_of_v<NewGRFSpecBase<Tindex>, Tspec>);
 
 	uint ui_count = 0; ///< Number of specs in this class potentially available to the user.
-	Tindex index; ///< Index of class within the list of classes.
+	Tindex index = static_cast<Tindex>(0); ///< Index of class within the list of classes.
 	std::vector<Tspec *> spec; ///< List of specifications.
 
 	/**