diff --git a/dsf/org.eclipse.cdt.dsf/src/org/eclipse/cdt/dsf/service/DsfSession.java b/dsf/org.eclipse.cdt.dsf/src/org/eclipse/cdt/dsf/service/DsfSession.java
index b764ec679bf..897016694c4 100644
--- a/dsf/org.eclipse.cdt.dsf/src/org/eclipse/cdt/dsf/service/DsfSession.java
+++ b/dsf/org.eclipse.cdt.dsf/src/org/eclipse/cdt/dsf/service/DsfSession.java
@@ -485,7 +485,7 @@ public class DsfSession
             for (Method method : methods) {
                 if (method.isAnnotationPresent(DsfServiceEventHandler.class)) {
                     Class<?>[] paramTypes = method.getParameterTypes();
-                    if (paramTypes.length > 1) {
+                    if (paramTypes.length != 1) {	// must have one and only param
                         throw new IllegalArgumentException("ServiceEventHandler method has incorrect number of parameters"); //$NON-NLS-1$
                     } 
                     retVal.add(method);