diff --git a/app/src/main/java/ua/acclorite/book_story/presentation/core/util/Extensions.kt b/app/src/main/java/ua/acclorite/book_story/presentation/core/util/Extensions.kt
index e08270ba..55bac524 100644
--- a/app/src/main/java/ua/acclorite/book_story/presentation/core/util/Extensions.kt
+++ b/app/src/main/java/ua/acclorite/book_story/presentation/core/util/Extensions.kt
@@ -47,6 +47,11 @@ fun Float.calculateProgress(digits: Int): String {
         .dropWhile { it == '-' }
 }
 
+fun Float.coerceAndPreventNaN(): Float {
+    if (isNaN()) return 0f
+    return this.coerceIn(0f, 1f)
+}
+
 @OptIn(ExperimentalFoundationApi::class)
 fun Modifier.noRippleClickable(
     enabled: Boolean = true,
diff --git a/app/src/main/java/ua/acclorite/book_story/presentation/screens/reader/data/ReaderViewModel.kt b/app/src/main/java/ua/acclorite/book_story/presentation/screens/reader/data/ReaderViewModel.kt
index 5ee5c335..0dd48f8f 100644
--- a/app/src/main/java/ua/acclorite/book_story/presentation/screens/reader/data/ReaderViewModel.kt
+++ b/app/src/main/java/ua/acclorite/book_story/presentation/screens/reader/data/ReaderViewModel.kt
@@ -36,6 +36,7 @@ import ua.acclorite.book_story.domain.util.Resource
 import ua.acclorite.book_story.domain.util.UIText
 import ua.acclorite.book_story.presentation.core.navigation.Screen
 import ua.acclorite.book_story.presentation.core.util.BaseViewModel
+import ua.acclorite.book_story.presentation.core.util.coerceAndPreventNaN
 import ua.acclorite.book_story.presentation.core.util.launchActivity
 import javax.inject.Inject
 import kotlin.math.roundToInt
@@ -617,8 +618,8 @@ class ReaderViewModel @Inject constructor(
 
             val currentIndex = index - startIndex
             val endIndex = endIndex - startIndex
-            (currentIndex / endIndex.toFloat()).coerceIn(0f, 1f)
-        }
+            (currentIndex / endIndex.toFloat())
+        }.coerceAndPreventNaN()
 
         _state.update {
             it.copy(
@@ -647,8 +648,9 @@ class ReaderViewModel @Inject constructor(
                 return 1f
             }
 
-            return@run ((firstVisibleItemIndex ?: listState.firstVisibleItemIndex) /
-                    (text.lastIndex).toFloat()).coerceIn(0f, 1f)
+            return@run (firstVisibleItemIndex ?: listState.firstVisibleItemIndex)
+                .div(text.lastIndex.toFloat())
+                .coerceAndPreventNaN()
         }
     }