diff --git a/extensions/media-preview/media/imagePreview.js b/extensions/media-preview/media/imagePreview.js
index d31728e76bc..91338ba0bc3 100644
--- a/extensions/media-preview/media/imagePreview.js
+++ b/extensions/media-preview/media/imagePreview.js
@@ -89,6 +89,9 @@
 			image.classList.remove('pixelated');
 			// @ts-ignore Non-standard CSS property
 			image.style.zoom = 'normal';
+			// Clear explicit dimensions so the image can scale-to-fit naturally
+			image.style.minWidth = '';
+			image.style.minHeight = '';
 			vscode.setState(undefined);
 		} else {
 			scale = clamp(newScale, MIN_SCALE, MAX_SCALE);
@@ -102,6 +105,17 @@
 			const dy = (window.scrollY + container.clientHeight / 2) / container.scrollHeight;
 
 			image.classList.remove('scale-to-fit');
+
+			// For images without intrinsic dimensions (e.g. SVGs with only
+			// a viewBox), set explicit pixel dimensions so that CSS zoom has
+			// something concrete to scale.
+			if (!image.naturalWidth || !image.naturalHeight) {
+				const baseWidth = image.clientWidth || container.clientWidth;
+				const baseHeight = image.clientHeight || container.clientHeight;
+				image.style.minWidth = baseWidth + 'px';
+				image.style.minHeight = baseHeight + 'px';
+			}
+
 			// @ts-ignore Non-standard CSS property
 			image.style.zoom = scale;
 
@@ -142,7 +156,14 @@
 			return;
 		}
 
-		scale = image.clientWidth / image.naturalWidth;
+		if (image.naturalWidth) {
+			scale = image.clientWidth / image.naturalWidth;
+		} else {
+			// For images without intrinsic dimensions (e.g. SVGs with
+			// only a viewBox), start at 1x since there is no meaningful
+			// natural size to compute a ratio from.
+			scale = 1;
+		}
 		updateScale(scale);
 	}