diff --git a/cache/src/main/java/dev/openrs2/cache/Js5Compression.kt b/cache/src/main/java/dev/openrs2/cache/Js5Compression.kt
index 206018f4c8..c0bd93e008 100644
--- a/cache/src/main/java/dev/openrs2/cache/Js5Compression.kt
+++ b/cache/src/main/java/dev/openrs2/cache/Js5Compression.kt
@@ -152,6 +152,10 @@ public object Js5Compression {
                         }
                         remaining -= n
                     }
+
+                    if (inputStream.read() != -1) {
+                        throw IOException("Uncompressed data overflow")
+                    }
                 }
 
                 return output.retain()