diff --git a/gwt-material/src/main/java/gwt/material/design/client/ui/MaterialCollapsible.java b/gwt-material/src/main/java/gwt/material/design/client/ui/MaterialCollapsible.java
index 80fbe50e3..6c4c2218d 100644
--- a/gwt-material/src/main/java/gwt/material/design/client/ui/MaterialCollapsible.java
+++ b/gwt-material/src/main/java/gwt/material/design/client/ui/MaterialCollapsible.java
@@ -256,7 +256,7 @@ public void setActive(int index, boolean active) {
         if (isAttached()) {
             if (index <= getWidgetCount()) {
                 if (index > 0) {
-                    activeWidget = getWidget(index);
+                    activeWidget = getWidget(index - 1);
                     if (activeWidget != null && activeWidget instanceof MaterialCollapsibleItem) {
                         ((MaterialCollapsibleItem) activeWidget).setActive(active);
                         reload();