diff --git a/devtools/client/themes/webconsole.css b/devtools/client/themes/webconsole.css
index 51968759f183..3d15055464c3 100644
--- a/devtools/client/themes/webconsole.css
+++ b/devtools/client/themes/webconsole.css
@@ -380,6 +380,9 @@ a {
 }
 
 .jsterm-input-node {
+  /* Always allow scrolling on input - it auto expands in js by setting height,
+     but don't want it to get bigger than the window. 24px = toolbar height. */
+  max-height: calc(90vh - 24px);
   background-image: -moz-image-rect(url("chrome://devtools/skin/themes/images/commandline-icon.png"), 0, 32, 16, 16);
   background-repeat: no-repeat;
   background-size: 16px 16px;