diff --git a/src/calibre/devices/cybookg3/driver.py b/src/calibre/devices/cybookg3/driver.py
index a8ce905b00..d3ccf85461 100644
--- a/src/calibre/devices/cybookg3/driver.py
+++ b/src/calibre/devices/cybookg3/driver.py
@@ -13,7 +13,7 @@ from calibre.devices.usbms.driver import USBMS
 import calibre.devices.cybookg3.t2b as t2b
 
 class CYBOOKG3(USBMS):
-    name           = 'Cybook Gen 3 Device Interface'
+    name           = 'Cybook Gen 3/Opus Device Interface'
     description    = _('Communicate with the Cybook eBook reader.')
     author         = _('John Schember')
     supported_platforms = ['windows', 'osx', 'linux']
@@ -31,7 +31,7 @@ class CYBOOKG3(USBMS):
     WINDOWS_MAIN_MEM = 'CYBOOK_GEN3__-FD'
     WINDOWS_CARD_A_MEM = 'CYBOOK_GEN3__-SD'
 
-    OSX_MAIN_MEM = 'Bookeen Cybook Gen3 -FD Media'
+    OSX_MAIN_MEM = ['Bookeen Cybook Gen3 -FD Media', 'Bookeen Cybook Opus -FD Media']
     OSX_CARD_A_MEM = 'Bookeen Cybook Gen3 -SD Media'
 
     MAIN_MEMORY_VOLUME_LABEL  = 'Cybook Gen 3 Main Memory'
diff --git a/src/calibre/ebooks/oeb/stylizer.py b/src/calibre/ebooks/oeb/stylizer.py
index da68dc2f69..1d3b0515d4 100644
--- a/src/calibre/ebooks/oeb/stylizer.py
+++ b/src/calibre/ebooks/oeb/stylizer.py
@@ -225,6 +225,7 @@ class Stylizer(object):
         if 'font-size' in style:
             size = style['font-size']
             if size == 'normal': size = 'medium'
+            if size == 'smallest': size = 'xx-small'
             if size in FONT_SIZE_NAMES:
                 style['font-size'] = "%dpt" % self.profile.fnames[size]
         return style
diff --git a/src/calibre/ebooks/oeb/transforms/flatcss.py b/src/calibre/ebooks/oeb/transforms/flatcss.py
index 7114c9736f..8ef5c42ea1 100644
--- a/src/calibre/ebooks/oeb/transforms/flatcss.py
+++ b/src/calibre/ebooks/oeb/transforms/flatcss.py
@@ -213,7 +213,10 @@ class CSSFlattener(object):
                             esize = 7
                         cssdict['font-size'] = fnums[esize]
                     else:
-                        cssdict['font-size'] = fnums[force_int(size)]
+                        try:
+                            cssdict['font-size'] = fnums[force_int(size)]
+                        except:
+                            cssdict['font-size'] = fnums[3]
                 del node.attrib['size']
         if 'color' in node.attrib:
             cssdict['color'] = node.attrib['color']