diff --git a/filters/email-gravatar.lua b/filters/email-gravatar.lua
index 3aad258..52cf426 100644
--- a/filters/email-gravatar.lua
+++ b/filters/email-gravatar.lua
@@ -15,7 +15,7 @@ function filter_open(email, page)
 end
 
 function filter_close()
-	html("<img src='//www.gravatar.com/avatar/" .. md5 .. "?s=13&amp;d=retro' width=13 height=13 alt='Gravatar' /> " .. buffer)
+	html("<img src='//www.gravatar.com/avatar/" .. md5 .. "?s=13&amp;d=retro' width='13' height='13' alt='Gravatar' /> " .. buffer)
 	return 0
 end
 
diff --git a/filters/email-gravatar.py b/filters/email-gravatar.py
index 88bc776..d70440e 100755
--- a/filters/email-gravatar.py
+++ b/filters/email-gravatar.py
@@ -36,4 +36,4 @@ sys.stdout = codecs.getwriter("utf-8")(sys.stdout.detach())
 md5 = hashlib.md5(email.encode()).hexdigest()
 text = sys.stdin.read().strip()
 
-print("<img src='//www.gravatar.com/avatar/" + md5 + "?s=13&amp;d=retro' width=13 height=13 alt='Gravatar' /> " + text)
+print("<img src='//www.gravatar.com/avatar/" + md5 + "?s=13&amp;d=retro' width='13' height='13' alt='Gravatar' /> " + text)