diff --git a/Data/Aeson/Encode/Builder.hs b/Data/Aeson/Encode/Builder.hs
--- a/Data/Aeson/Encode/Builder.hs
+++ b/Data/Aeson/Encode/Builder.hs
@@ -181,12 +181,13 @@
         !(T dh dl)  = twoDigits d
         encodeYear y
             | y >= 1000 = B.integerDec y
-            | y > 0 =
-                let (ab,c) = fromIntegral y `quotRem` 10
-                    (a,b)  = ab `quotRem` 10
-                in BP.primBounded (ascii4 ('0',(digit a,(digit b,digit c)))) ()
-            | otherwise =
-                error "Data.Aeson.Encode.Builder.day:  years BCE not supported"
+            | y >= 0    = BP.primBounded (ascii4 (padYear y)) ()
+            | y >= -999 = BP.primBounded (ascii5 ('-',padYear (- y))) ()
+            | otherwise = B.integerDec y
+        padYear y =
+            let (ab,c) = fromIntegral y `quotRem` 10
+                (a,b)  = ab `quotRem` 10
+            in ('0',(digit a,(digit b,digit c)))
 {-# INLINE day #-}
 
 timeOfDay :: TimeOfDay -> Builder
diff --git a/aeson.cabal b/aeson.cabal
--- a/aeson.cabal
+++ b/aeson.cabal
@@ -1,5 +1,5 @@
 name:            aeson
-version:         0.11.2.1
+version:         0.11.3.0
 license:         BSD3
 license-file:    LICENSE
 category:        Text, Web, JSON
diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,9 @@
 For the latest version of this document, please see [https://github.com/bos/aeson/blob/master/changelog.md](https://github.com/bos/aeson/blob/master/changelog.md).
 
+### 0.11.3.0
+
+* Backported support for `Day`s BCE from aeson-1.1.0.0
+
 ### 0.11.2.0
 
 * Enable `PolyKinds` to generalize `Proxy`, `Tagged`, and `Const` instances.