diff --git a/src/material/expansion/expansion-panel.scss b/src/material/expansion/expansion-panel.scss
index 2ea2a908ea27..3c772eda8fe8 100644
--- a/src/material/expansion/expansion-panel.scss
+++ b/src/material/expansion/expansion-panel.scss
@@ -10,6 +10,7 @@
   margin: 0;
   border-radius: $border-radius;
   overflow: hidden;
+  position: relative;
   transition: margin 225ms $mat-fast-out-slow-in-timing-function,
       mat-elevation-transition-property-value();