diff --git a/examples/compare-image.html b/examples/compare-image.html
index d9be8d39..01a09651 100644
--- a/examples/compare-image.html
+++ b/examples/compare-image.html
@@ -33,6 +33,7 @@
         )
 
         const container = document.querySelector('#viewport')
+
         // Provide fixedImage and compare as createViewer options example:
         // const viewer = await itkVtkViewer.createViewer(container, {
         //   rotate: false,
@@ -45,24 +46,24 @@
         const viewer = await itkVtkViewer.createViewer(container, {
           rotate: false,
         })
-        viewer.setImage(fixedImageUrl, 'fixed') // fixed image must be first one added
+        viewer.setImage(fixedImageUrl, 'Fixed') // fixed image must be first one added
         viewer.setImage(imageUrl, 'Image')
 
-        viewer.setCompareImages('fixed', 'Image', {
+        viewer.setCompareImages('Fixed', 'Image', {
           method: 'checkerboard',
           swapImageOrder: true,
         })
 
         setTimeout(
           () =>
-            viewer.setCompareImages('fixed', 'Image', {
+            viewer.setCompareImages('Fixed', 'Image', {
               method: 'disabled',
             }),
           2000
         )
         setTimeout(
           () =>
-            viewer.setCompareImages('fixed', 'Image', {
+            viewer.setCompareImages('Fixed', 'Image', {
               method: 'checkerboard',
               pattern: [1, 2, 3],
             }),
@@ -71,7 +72,7 @@
 
         setTimeout(
           () =>
-            viewer.setCompareImages('fixed', 'Image', {
+            viewer.setCompareImages('Fixed', 'Image', {
               method: 'checkerboard',
               pattern: [1, 2, 3],
               swapImageOrder: true,
diff --git a/src/createViewer.js b/src/createViewer.js
index d8316aef..0fb60518 100644
--- a/src/createViewer.js
+++ b/src/createViewer.js
@@ -1264,7 +1264,7 @@ const createViewer = async (
 
   // must come before moving/main image
   if (fixedImage) {
-    await publicAPI.setImage(fixedImage, 'fixed') // must await so fixedImage is the first one
+    await publicAPI.setImage(fixedImage, 'Fixed') // must await so fixedImage is the first one
   }
 
   if (imageMultiscale) {
@@ -1276,7 +1276,7 @@ const createViewer = async (
   }
 
   if (fixedImage && imageMultiscale) {
-    publicAPI.setCompareImages('fixed', imageMultiscale.name, compare)
+    publicAPI.setCompareImages('Fixed', imageMultiscale.name, compare)
   }
 
   if (!context.use2D) {