diff --git a/src/nostalgia/core/ptidxconv.hpp b/src/nostalgia/core/ptidxconv.hpp
index 6b5ec7f92..9c78b965b 100644
--- a/src/nostalgia/core/ptidxconv.hpp
+++ b/src/nostalgia/core/ptidxconv.hpp
@@ -28,6 +28,10 @@ constexpr std::size_t ptToIdx(const geo::Point &pt, int c) noexcept {
 
 [[nodiscard]]
 constexpr geo::Point idxToPt(int i, int c) noexcept {
+	// prevent divide by zeros
+	if (!c) {
+		++c;
+	}
 	const auto t = i / PixelsPerTile; // tile number
 	const auto iti = i % PixelsPerTile; // in tile index
 	const auto tc = t % c; // tile column