diff --git a/gradle.properties b/gradle.properties
index 8f1fce5..16190e0 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,3 +1,3 @@
 # These properties are only used when this repository is built stand-alone, outside of devenv.
 org.gradle.jvmargs=-Xms512M -Xmx2G -Xss8M
-systemProp.spoofax2Version=2.5.20
+systemProp.spoofax2Version=2.5.21