diff --git a/Text/Pandoc/Arbitrary.hs b/Text/Pandoc/Arbitrary.hs
--- a/Text/Pandoc/Arbitrary.hs
+++ b/Text/Pandoc/Arbitrary.hs
@@ -48,6 +48,9 @@
                    , (10,  liftM Superscript $ arbInlines (n-1))
                    , (10,  liftM Subscript $ arbInlines (n-1))
                    , (10,  liftM SmallCaps $ arbInlines (n-1))
+                   , (10,  do x1 <- arbAttr
+                              x2 <- arbInlines (n-1)
+                              return $ Span x1 x2)
                    , (10,  do x1 <- arbitrary
                               x2 <- arbInlines (n-1)
                               return $ Quoted x1 x2)
@@ -102,6 +105,9 @@
                                         x2 <- arbInlines (n-1)
                                         return (x2,x1)
                              return $ DefinitionList items)
+                   , (5,  do x1 <- arbAttr
+                             x2 <- listOf1 $ arbBlock (n-1)
+                             return $ Div x1 x2)
                    , (2, do rs <- choose (1 :: Int, 4)
                             cs <- choose (1 :: Int, 4)
                             x1 <- arbInlines (n-1)
diff --git a/Text/Pandoc/Builder.hs b/Text/Pandoc/Builder.hs
--- a/Text/Pandoc/Builder.hs
+++ b/Text/Pandoc/Builder.hs
@@ -478,19 +478,25 @@
       -> Blocks
 table caption cellspecs headers rows = singleton $
   Table (toList caption) aligns widths
-      (map toList headers) (map (map toList) rows)
+      (map toList headers') (map (map toList) rows)
    where (aligns, widths) = unzip cellspecs
+         numcols  = case (headers:rows) of
+                         [] -> 0
+                         xs -> maximum (map length xs)
+         headers' = if null headers
+                       then replicate numcols mempty
+                       else headers
 
 -- | A simple table without a caption.
 simpleTable :: [Blocks]   -- ^ Headers
             -> [[Blocks]] -- ^ Rows
             -> Blocks
-simpleTable headers = table mempty (mapConst defaults headers) headers
+simpleTable headers rows =
+  table mempty (replicate numcols defaults) headers rows
   where defaults = (AlignDefault, 0)
+        numcols  = case (headers:rows) of
+                        [] -> 0
+                        xs -> maximum (map length xs)
 
 divWith :: Attr -> Blocks -> Blocks
 divWith attr = singleton . Div attr . toList
-
-mapConst :: Functor f => b -> f a -> f b
-mapConst = fmap . const
-
diff --git a/Text/Pandoc/Walk.hs b/Text/Pandoc/Walk.hs
--- a/Text/Pandoc/Walk.hs
+++ b/Text/Pandoc/Walk.hs
@@ -91,12 +91,12 @@
 where
 import Control.Applicative ((<$>))
 import Text.Pandoc.Definition
-import Text.Pandoc.Builder ((<>))
 import qualified Data.Traversable as T
 import Data.Traversable (Traversable)
 import qualified Data.Foldable as F
 import Data.Foldable (Foldable)
 #if MIN_VERSION_base(4,8,0)
+import Data.Monoid ((<>))
 #else
 import Data.Monoid
 #endif
diff --git a/changelog b/changelog
--- a/changelog
+++ b/changelog
@@ -1,3 +1,13 @@
+[1.17.1]
+
+  * Better consistency in simpleTable and table (jgm/pandoc#3648).
+    If `headers` is empty, we populate it with empty cells, using the rows
+    to determine number of columns.  We also ensure that there are numcols
+    alignments and column widths.
+  * Make sure Div and Span occur in Arbitrary instances.
+  * Bump dependency upper bounds.
+  * Removed unused mapConst.
+
 [1.17.0.5]
 
   * Allow aeson 1.1.
diff --git a/pandoc-types.cabal b/pandoc-types.cabal
--- a/pandoc-types.cabal
+++ b/pandoc-types.cabal
@@ -1,5 +1,5 @@
 Name:                pandoc-types
-Version:             1.17.0.5
+Version:             1.17.1
 Synopsis:            Types for representing a structured document
 Description:         @Text.Pandoc.Definition@ defines the 'Pandoc' data
                      structure, which is used by pandoc to represent
@@ -48,10 +48,10 @@
   Other-modules:     Paths_pandoc_types
   Build-depends:     base >= 4 && < 5,
                      containers >= 0.3,
-                     syb >= 0.1 && < 0.7,
+                     syb >= 0.1 && < 0.8,
                      ghc-prim >= 0.2,
                      bytestring >= 0.9 && < 0.11,
-                     aeson >= 0.6.2 && < 1.2,
+                     aeson >= 0.6.2 && < 1.3,
                      QuickCheck >= 2
   if impl(ghc < 7.10)
     Build-depends:   deepseq-generics >= 0.1 && < 0.2
@@ -65,13 +65,13 @@
   build-depends:       base,
                        pandoc-types,
                        syb,
-                       aeson >= 0.6.2 && < 1.2,
+                       aeson >= 0.6.2 && < 1.3,
                        containers >= 0.3,
                        bytestring >= 0.9 && < 0.11,
                        test-framework >= 0.3 && < 0.9,
                        test-framework-hunit >= 0.2 && < 0.4,
                        test-framework-quickcheck2 >= 0.2.9 && < 0.4,
-                       QuickCheck >= 2.4 && < 2.10,
-                       HUnit >= 1.2 && < 1.6,
+                       QuickCheck >= 2.4 && < 2.11,
+                       HUnit >= 1.2 && < 1.7,
                        string-qq == 0.0.2
   ghc-options:         -threaded -rtsopts -with-rtsopts=-N
diff --git a/test/test-pandoc-types.hs b/test/test-pandoc-types.hs
--- a/test/test-pandoc-types.hs
+++ b/test/test-pandoc-types.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE OverloadedStrings, QuasiQuotes, FlexibleContexts #-}
+{-# LANGUAGE OverloadedStrings, QuasiQuotes, FlexibleContexts, CPP #-}
 
 import Text.Pandoc.Definition
 import Text.Pandoc.Walk
@@ -14,6 +14,11 @@
 import qualified Data.Map as M
 import Data.String.QQ
 import Data.ByteString.Lazy (ByteString)
+#if MIN_VERSION_base(4,8,0)
+#else
+import Data.Monoid
+#endif
+
 
 p_walk :: (Typeable a, Walkable a Pandoc)
        => (a -> a) -> Pandoc -> Bool