diff --git a/cpp/src/monoformat_fontreader.hpp b/cpp/src/monoformat_fontreader.hpp
index dcdf69a..5418e0e 100644
--- a/cpp/src/monoformat_fontreader.hpp
+++ b/cpp/src/monoformat_fontreader.hpp
@@ -558,6 +558,7 @@ public:
             }
 
             // FIXME: newline support
+            // also FIXME: call ensureAdvance when handling newline
             if (cp == '\n') {
                 cp = ' ';
             }
@@ -570,6 +571,8 @@ public:
             boundingBox = combineBoundingBoxes(boundingBox, dims->boundingBox);
         }
 
+        boundingBox = ensureAdvance(boundingBox, advance);
+
         return RenderedDimensions{advance, boundingBox};
     }
 
@@ -619,6 +622,22 @@ private:
         }
     }
 
+    static std::optional<Rectangle> ensureAdvance(std::optional<Rectangle> a, Point advance) {
+        if (!a) {
+            return std::nullopt;
+        }
+
+        // FIXME: once we support multi-line also handle y component
+
+        auto bottomRight = a->getBottomRight();
+        if ((bottomRight.x + 1) < advance.x) {
+            bottomRight.x = advance.x - 1;
+            return Rectangle::fromCorners(a->topLeft, bottomRight);
+        } else {
+            return a;
+        }
+    }
+
     template<typename Display>
     static std::expected<RenderedDimensions, LookupError> renderGlyph(std::uint32_t cp, Point position, FontReader const& font, Display& display, typename Display::Color fontColor, std::optional<typename Display::Color> bgColor) {
         auto glyph_ = font.tryRetrieveGlyphData(cp);