diff --git a/build.sbt b/build.sbt
index ce5dbc1f..e53b9869 100644
--- a/build.sbt
+++ b/build.sbt
@@ -58,7 +58,7 @@ ThisBuild / licenses := Seq(License.Apache2)
 // scala versions
 val scala3 = "3.3.7"
 val scala213 = "2.13.17"
-val scala212 = "2.12.20"
+val scala212 = "2.12.21"
 val scalaDefault = scala213
 val scala3Projects = List(
   "shared",