diff --git a/examples/test/test-tooltips.html b/examples/test/test-tooltips.html
index 054e047b0..24bcf98cd 100644
--- a/examples/test/test-tooltips.html
+++ b/examples/test/test-tooltips.html
@@ -49,7 +49,9 @@ <h1>Test multiple instances / tooltips</h1>
                 x: 4500000,
                 y: 2900000,
                 z: 2000,
-            }).addZoomButtons()
+            })
+                .addZoomButtons()
+                .addFullscreenButton()
 
             //define multi resolution dataset
             const dataset = new gridviz.MultiResolutionDataset(
diff --git a/src/core/Tooltip.js b/src/core/Tooltip.js
index a3e0fe180..1f98963d5 100644
--- a/src/core/Tooltip.js
+++ b/src/core/Tooltip.js
@@ -69,6 +69,7 @@ export class Tooltip {
         this.tooltip.style('pointer-events', 'none')
         this.tooltip.style('opacity', '0')
         this.tooltip.style('text-wrap', 'nowrap')
+        this.tooltip.style('z-index', 99999999) // important for leaflet-gridviz etc
 
         // these placeholders are needed to prevent an infinite DOM resizeObserver loop:
         this.tooltip.style('left', '0')