diff --git a/doc/default_theme.rasi b/doc/default_theme.rasi
index 127cbb33..e8f541d8 100644
--- a/doc/default_theme.rasi
+++ b/doc/default_theme.rasi
@@ -79,7 +79,7 @@ element-text {
 }
 element-icon {
     background-color: rgba ( 0, 0, 0, 0 % );
-    size:             1.2000ch ;
+    size:             1.2000em ;
     text-color:       inherit;
 }
 window {