diff --git a/postgresql-simple.cabal b/postgresql-simple.cabal
--- a/postgresql-simple.cabal
+++ b/postgresql-simple.cabal
@@ -1,5 +1,5 @@
 Name:                postgresql-simple
-Version:             0.4.5.0
+Version:             0.4.6.0
 Synopsis:            Mid-Level PostgreSQL client library
 Description:
     Mid-Level PostgreSQL client library, forked from mysql-simple.
@@ -81,7 +81,7 @@
 source-repository this
   type:     git
   location: http://github.com/lpsmith/postgresql-simple
-  tag:      v0.4.5.0
+  tag:      v0.4.6.0
 
 test-suite test
   type:           exitcode-stdio-1.0
diff --git a/src/Database/PostgreSQL/Simple/Time.hs b/src/Database/PostgreSQL/Simple/Time.hs
--- a/src/Database/PostgreSQL/Simple/Time.hs
+++ b/src/Database/PostgreSQL/Simple/Time.hs
@@ -75,6 +75,7 @@
      , zonedTimestampToBuilder
      , localTimestampToBuilder
      , unboundedToBuilder
+     , nominalDiffTimeToBuilder
      ) where
 
 import Database.PostgreSQL.Simple.Time.Implementation
diff --git a/src/Database/PostgreSQL/Simple/Time/Implementation.hs b/src/Database/PostgreSQL/Simple/Time/Implementation.hs
--- a/src/Database/PostgreSQL/Simple/Time/Implementation.hs
+++ b/src/Database/PostgreSQL/Simple/Time/Implementation.hs
@@ -229,6 +229,17 @@
 dateToBuilder  :: Date -> Builder
 dateToBuilder  = unboundedToBuilder dayToBuilder
 
+nominalDiffTimeToBuilder :: NominalDiffTime -> Builder
+nominalDiffTimeToBuilder xyz
+    | yz < 500000 = sign ++ integral x
+    | otherwise   = sign ++ integral x ++ fromChar '.' ++  showD6 y
+  where
+    -- A kludge to work around the fact that Data.Fixed isn't very fast and
+    -- doesn't give me access to the MkFixed constructor.
+    sign = if xyz >= 0 then mempty else fromChar '-'
+    (x,yz) = ((unsafeCoerce (abs xyz) :: Integer) + 500000)  `quotRem` 1000000000000
+    (fromIntegral -> y, _z) = yz `quotRem` 1000000
+
 showSeconds :: Pico -> Builder
 showSeconds xyz
     | yz == 0   = pad2 x
diff --git a/src/Database/PostgreSQL/Simple/ToField.hs b/src/Database/PostgreSQL/Simple/ToField.hs
--- a/src/Database/PostgreSQL/Simple/ToField.hs
+++ b/src/Database/PostgreSQL/Simple/ToField.hs
@@ -30,7 +30,7 @@
 import Data.Int (Int8, Int16, Int32, Int64)
 import Data.List (intersperse)
 import Data.Monoid (mappend)
-import Data.Time (Day, TimeOfDay, LocalTime, UTCTime, ZonedTime)
+import Data.Time (Day, TimeOfDay, LocalTime, UTCTime, ZonedTime, NominalDiffTime)
 import Data.Typeable (Typeable)
 import Data.Word (Word, Word8, Word16, Word32, Word64)
 import {-# SOURCE #-} Database.PostgreSQL.Simple.ToRow
@@ -225,6 +225,7 @@
     toField = toField . LT.toStrict
     {-# INLINE toField #-}
 
+
 instance ToField UTCTime where
     toField = Plain . inQuotes . utcTimeToBuilder
     {-# INLINE toField #-}
@@ -259,6 +260,10 @@
 
 instance ToField Date where
     toField = Plain . inQuotes . dateToBuilder
+    {-# INLINE toField #-}
+
+instance ToField NominalDiffTime where
+    toField = Plain . inQuotes . nominalDiffTimeToBuilder
     {-# INLINE toField #-}
 
 instance (ToField a) => ToField (PGArray a) where