diff --git a/crypto/src/test/java/dev/openrs2/crypto/IsaacRandomTest.kt b/crypto/src/test/java/dev/openrs2/crypto/IsaacRandomTest.kt
index db3e9b44..27897cf7 100644
--- a/crypto/src/test/java/dev/openrs2/crypto/IsaacRandomTest.kt
+++ b/crypto/src/test/java/dev/openrs2/crypto/IsaacRandomTest.kt
@@ -68,7 +68,7 @@ object IsaacRandomTest {
 
             for (line in lines) {
                 for (i in line.indices step 8) {
-                    elements += Integer.parseUnsignedInt(line.substring(i, i + 8), 16)
+                    elements += Integer.parseUnsignedInt(line, i, i + 8, 16)
                 }
             }