diff --git a/build.gradle b/build.gradle
index 0235900..3acded6 100644
--- a/build.gradle
+++ b/build.gradle
@@ -11,7 +11,7 @@ ext {
     jmeTarget = '' // distinguish non-JME libraries built for specific JME releases
 
     // module coordinates of external dependencies:
-    heartCoordinates = 'com.github.stephengold:Heart:8.8.0' + jmeTarget
+    heartCoordinates = 'com.github.stephengold:Heart:9.0.0' + jmeTarget
 
     // current versions of libraries:
     jme3Version = '3.6.1-stable'