diff --git a/themes/tiddlywiki/seamless/base.tid b/themes/tiddlywiki/seamless/base.tid
index 159b5fa36..21656aa9e 100644
--- a/themes/tiddlywiki/seamless/base.tid
+++ b/themes/tiddlywiki/seamless/base.tid
@@ -27,7 +27,7 @@ Rules copied from Snow White
 }
 
 .tc-modal-displayed {
-	-webkit-filter: blur(4px);
+	<<filter "blur(4px)">>
 }
 
 .tc-modal {
diff --git a/themes/tiddlywiki/snowwhite/base.tid b/themes/tiddlywiki/snowwhite/base.tid
index a1c08d9a0..fae5bc170 100644
--- a/themes/tiddlywiki/snowwhite/base.tid
+++ b/themes/tiddlywiki/snowwhite/base.tid
@@ -71,7 +71,7 @@ canvas.tc-edit-bitmapeditor  {
 }
 
 .tc-modal-displayed {
-	-webkit-filter: blur(4px);
+	<<filter "blur(4px)">>
 }
 
 .tc-modal {