diff --git a/app/modules/toolkits/cdk_wrapper.py b/app/modules/toolkits/cdk_wrapper.py
index f8d1478..01d175d 100644
--- a/app/modules/toolkits/cdk_wrapper.py
+++ b/app/modules/toolkits/cdk_wrapper.py
@@ -36,7 +36,7 @@
     if not os.path.exists(centresjar_path):
         jar_path = pystow.ensure("STOUT-V2", url=centres_path)
 
-    startJVM("-ea", classpath=[cdkjar_path, srujar_path, centresjar_path], "-Xmx4096M")
+    startJVM("-ea", "-Xmx4096M", classpath=[cdkjar_path, srujar_path, centresjar_path])
     cdk_base = "org.openscience.cdk"