diff --git a/build/macosx/run.sh b/build/macosx/run.sh
index 29b979d27..bb8d49b27 100755
--- a/build/macosx/run.sh
+++ b/build/macosx/run.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 
-CLASSPATH=:lib:lib/build:lib/pde.jar:lib/antlr.jar:lib/oro.jar:lib/registry.jar
+CLASSPATH=:lib:lib/build:lib/pde.jar:lib/antlr.jar:lib/oro.jar:lib/registry.jar:lib/RXTXcomm.jar
 
 export CLASSPATH