diff --git a/tools/build/markdown/generate-graphics-module.js b/tools/build/markdown/generate-graphics-module.js
index 2164fb6c..078a5d06 100644
--- a/tools/build/markdown/generate-graphics-module.js
+++ b/tools/build/markdown/generate-graphics-module.js
@@ -23,12 +23,13 @@ function generateGraphicsModule(code, width, height) {
 
         const example = new Example(undefined, ${width}, ${height}, (w,h) => {
             const canvas = CanvasBuilder.createCanvas(w,h);
+            const ctx = canvas.getContext('2d');
+
+            // as this is node-canvas, we need to shim some functions:
             canvas.addEventListener = canvas.setAttribute = noop;
             canvas.classList = { add: noop };
             canvas.style = {};
-
-            const ctx = canvas.getContext('2d');
-            ctx.getTransform = () => ctx.currentTransform; // node-canvas lacks getTransform() support?
+            ctx.getTransform = () => ctx.currentTransform;
 
             return { canvas, ctx};
         });
diff --git a/tools/build/markdown/preprocess-graphics-element.js b/tools/build/markdown/preprocess-graphics-element.js
index c64e2596..b38d101d 100644
--- a/tools/build/markdown/preprocess-graphics-element.js
+++ b/tools/build/markdown/preprocess-graphics-element.js
@@ -119,7 +119,7 @@ async function generateFallbackImage(src, width, height) {
   const start = dataURI.indexOf(`base64,`) + 7;
   const imageData = Buffer.from(dataURI.substring(start), `base64`);
 
-  fs.ensureDirSync(path.dirname(destPath));
+  fs.ensureDirSync(path.dirname(filename));
   fs.writeFileSync(filename, imageData);
   console.log(`Generated fallback image for ${src}`);