diff --git a/gradle.properties b/gradle.properties
index 7eb1c7c9..840d1f98 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -5,14 +5,14 @@ org.gradle.parallel=true
 #org.gradle.workers.max=8
 
 
-kotlinVersion=2.0.10
+kotlinVersion=1.9.25
 
 # Coroutines 1.9 (currently RC) requires Kotlin 2.0
 coroutinesVersion=1.8.1
 # Ktor 3.x (RC right now) requires Kotlin 2.0
 ktorVersion=2.3.12
 kotlinxDateTimeVersion=0.5.0
-kotlinxSerializationVersion=1.7.1
+kotlinxSerializationVersion=1.6.2
 atomicfuVersion=0.25.0
 
 klfVersion=1.6.0