diff --git a/chrome/content/zotero/preferences/preferences_firefox.xul b/chrome/content/zotero/preferences/preferences_firefox.xul
index 5292d0288..07dc62428 100644
--- a/chrome/content/zotero/preferences/preferences_firefox.xul
+++ b/chrome/content/zotero/preferences/preferences_firefox.xul
@@ -50,10 +50,13 @@
 			<vbox style="margin-left: 1em">
 				<checkbox id="zotero-proxies-autoRecognize" label="&zotero.preferences.proxies.autoRecognize;"
 					command="zotero-proxies-update"/>
-				<hbox style="display: block">
-					<checkbox id="zotero-proxies-disableByDomain-checkbox" label="&zotero.preferences.proxies.disableByDomain;"
+				<hbox style="display: block; line-height: 1.75em">
+					<checkbox id="zotero-proxies-disableByDomain-checkbox"
+						label="&zotero.preferences.proxies.disableByDomain;"
 						command="zotero-proxies-update"/>
-					<textbox id="zotero-proxies-disableByDomain-textbox" onchange="Zotero_Preferences.Proxies.updateProxyPrefs()"/>
+					<textbox id="zotero-proxies-disableByDomain-textbox"
+						onchange="Zotero_Preferences.Proxies.updateProxyPrefs()"
+						flex="1" style="max-width: 11.75em"/>
 				</hbox>
 			</vbox>