diff --git a/src/routes/lesson/[part]/[name]/+page.svelte b/src/routes/lesson/[part]/[name]/+page.svelte
index 76795fb..c9961cb 100644
--- a/src/routes/lesson/[part]/[name]/+page.svelte
+++ b/src/routes/lesson/[part]/[name]/+page.svelte
@@ -493,9 +493,10 @@
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+ {#each [data.lessons.findIndex(l => l.slug === lesson.slug)] as currentIndex}
- {#if data.lessons.indexOf(lesson) > 0}
- {@const prevLesson = data.lessons[data.lessons.indexOf(lesson) - 1]}
+ {#if currentIndex > 0}
+ {@const prevLesson = data.lessons[currentIndex - 1]}
+ {/each}