diff --git a/src/pyj/dom.pyj b/src/pyj/dom.pyj
index 3ca575aa8c..be926a2ca4 100644
--- a/src/pyj/dom.pyj
+++ b/src/pyj/dom.pyj
@@ -92,6 +92,15 @@ def element(elem_id, child_selector):
         ans = ans.querySelector(child_selector)
     return ans
 
+def selector(id_selector, *args):
+    ans = '#' + id_selector
+    for x in args:
+        ans += ' ' + x
+    return ans
+
+def rule(id_selector, *args, **kw):
+    return build_rule(selector(id_selector, *args), **kw)
+
 def unique_id(prefix):
     prefix = prefix or 'auto-id'
     unique_id.counts[prefix] = num = (unique_id.counts[prefix] or 0) + 1
diff --git a/src/pyj/read_book/prefs/font_size.pyj b/src/pyj/read_book/prefs/font_size.pyj
index 0b8743f8bf..e1277cc938 100644
--- a/src/pyj/read_book/prefs/font_size.pyj
+++ b/src/pyj/read_book/prefs/font_size.pyj
@@ -2,8 +2,10 @@
 # License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
 from __python__ import hash_literals, bound_methods
 
-from dom import unique_id, set_css, add_extra_css, build_rule
+from dom import unique_id, set_css, add_extra_css, rule, element
 from elementmaker import E
+from gettext import gettext as _
+from widgets import create_button
 from book_list.globals import get_session_data, get_boss
 from book_list.theme import get_color
 
@@ -11,8 +13,9 @@ CONTAINER = unique_id('font-size-prefs')
 QUICK = unique_id('quick')
 
 add_extra_css(def():
-    style = build_rule('#' + QUICK + ' li.current', background_color=get_color('window-background2'))
-    style += build_rule('#' + QUICK + ' li:hover', background_color=get_color('window-background2'))
+    style = rule(QUICK, 'li.current', background_color=get_color('window-background2'))
+    style += rule(QUICK, 'li:hover', background_color=get_color('window-background2'))
+    style += rule(CONTAINER, 'a:hover', color='red')
     return style
 )
 
@@ -27,10 +30,20 @@ def set_quick_size(ev):
     sz = int(li.dataset.sz)
     change_font_size(sz)
 
+def set_custom_size(ev):
+    sz = int(element(CONTAINER, 'input').value)
+    change_font_size(sz)
+
+def show_custom_size(ev):
+    c = element(CONTAINER)
+    for child in c.childNodes:
+        child.style.display = 'none'
+    c.lastChild.style.display = 'block'
+
 def create_font_size_panel(container, close):
     container.appendChild(E.div(id=CONTAINER,
         style='margin:15vh auto; max-width: 500px; border-radius: 8px; border: solid 1px currentColor; padding:1ex 1rem',
-        onclick=def(ev): ev.preventDefault(), ev.stopPropagation
+        onclick=def(ev): ev.preventDefault(), ev.stopPropagation()
     ))
     container = container.lastChild
     container.style.backgroundColor = get_color('window-background')
@@ -42,5 +55,19 @@ def create_font_size_panel(container, close):
         quick.appendChild(set_css(E.li('Aa', title='{} px'.format(sz), class_='current' if cfs is sz else '', data_sz=str(sz), onclick=def(ev):set_quick_size(ev), close();),
             display='inline-block', font_size=sz + 'px', padding='5px', cursor='pointer', border_radius='2px'))
 
+    container.appendChild(E.div(
+        E.a(_('Custom size'), href='javascript:void', onclick=show_custom_size, style='cursor:pointer'),
+        style='text-align: right; color: blue; font-size: smaller; margin-top: 2ex'
+    ))
+
+    container.appendChild(E.div(style='display:none',
+        E.div(E.label(_('Font size (pixels):'), '\xa0', E.input(type='number', min=8, max=60, step=1, value=str(sd.get('base_font_size'))))),
+    E.div(style='text-align:right; margin-top:1ex; display:flex; justify-content: flex-end',
+            create_button(_('OK'), 'check', def(): set_custom_size(), close();), E.span('\xa0'),
+            create_button(_('Cancel'), action=close)
+    )))
+
+
+
 def develop(container):
     create_font_size_panel(container, def():pass;)