diff --git a/Data/Presburger/Omega/Expr.hs b/Data/Presburger/Omega/Expr.hs
--- a/Data/Presburger/Omega/Expr.hs
+++ b/Data/Presburger/Omega/Expr.hs
@@ -515,7 +515,8 @@
 appPrec = 10
 mulPrec = 7
 addPrec = 6
-cmpPrec = 5                     -- Less-than, equal
+cmpPrec = 4                     -- Less-than, equal
+andPrec = 3
 lamPrec = 0
 
 -- An environment for showing expressions.
@@ -594,20 +595,16 @@
     case expression
     of CAUE Conj lit es
            | lit        -> let texts = map (showsBoolExprPrec env 0) es
-                           in texts `showSepBy` showString " |&&| "
+                           in showParen (n >= andPrec) $
+                              texts `showSepBy` showString " |&&| "
            | otherwise  -> showString "falseE"
        CAUE Disj lit es
            | lit        -> showString "trueE"
            | otherwise  -> let texts = map (showsBoolExprPrec env 0) es
                            in showParen (n >= appPrec) $
                               showString "disjE " . showsList texts
-       PredE IsGEZ e    -> showParen (n >= appPrec) $ showGEZ env e
-       PredE p e        -> let operator =
-                                   case p
-                                   of IsZero -> showString "isZeroE "
-                                      IsGEZ  -> showString "isNonnegativeE "
-                           in showParen (n >= appPrec) $
-                              operator . showsIntExprPrec env appPrec e
+       PredE IsGEZ e    -> showGEZ env n e
+       PredE IsZero e   -> showEQZ env n e
        NotE e           -> showString "notE " . showsBoolExprPrec env appPrec e
        LitE True        -> showString "trueE"
        LitE False       -> showString "falseE"
@@ -622,8 +619,15 @@
 -- Use ">" if it gets rid of a term, otherwise use ">=".
 -- If the left side of the inequality is an integer literal,
 -- then move it to the right 
-showGEZ :: ShowsEnv -> IntExpr -> ShowS
-showGEZ env (CAUE Sum lit es) =
+showGEZ :: ShowsEnv -> Int -> IntExpr -> ShowS
+showGEZ env prec e =
+    showParen (prec >= cmpPrec) $
+    case e
+    of LitE n          -> showGEZ' env n []
+       CAUE Sum lit es -> showGEZ' env lit es
+       _               -> showGEZ' env 0 [e]
+
+showGEZ' env lit es =
     -- Partition into terms that will go on the left (positive) and right
     -- (negative) sides of the inequality.  Try to get rid of a '1' by
     -- using a greater-than sign.
@@ -659,6 +663,23 @@
       gt = showString " |>| "
       le = showString " |<=| "
       lt = showString " |<| "
+
+
+-- Show a comparison-to-zero prettily.
+-- If it is a summation with only one term, then we show it as
+--   "term |==| literal"
+-- Otherwise we show it as an application of "isZeroE".
+showEQZ :: ShowsEnv -> Int -> IntExpr -> ShowS
+showEQZ env prec (CAUE Sum lit [e]) =
+    showParen (prec >= cmpPrec) $
+    (showsIntExprPrec env cmpPrec e .
+     showString " |==| " .
+     showsIntExprPrec env cmpPrec (LitE lit)
+    )
+
+showEQZ env prec e =
+    showParen (prec >= appPrec) $
+    showString "isZeroE " . showsIntExprPrec env appPrec e
 
 -- Partition a sum term based on the sign it is displayed with.
 -- Negative-signed terms are multiplied by -1 to make them positive.
diff --git a/Omega.cabal b/Omega.cabal
--- a/Omega.cabal
+++ b/Omega.cabal
@@ -1,6 +1,6 @@
-Cabal-Version:		>= 1.2.3 && < 1.8
+Cabal-Version:		>= 1.2.3 && < 1.9
 Name:			Omega
-Version:		0.2.0
+Version:		0.2.1
 Build-Type:		Custom
 License:		BSD3
 License-File:		LICENSE
diff --git a/Setup.hs b/Setup.hs
--- a/Setup.hs
+++ b/Setup.hs
@@ -142,8 +142,7 @@
 
   -- Get 'ar' and 'ld' programs
   let verb = fromFlagOrDefault Verbosity.normal $ buildVerbosity flags
-  (arPgm, _) <- requireProgram verb arProgram AnyVersion (withPrograms lbi)
-  let runAr = rawSystemProgram verb arPgm
+  let runAr = rawSystemProgramConf verb arProgram (withPrograms lbi)
 
   -- Build the C++ source file (and Omega library, if configured)
   -- Makefile's behavior is controlled by output of 'configure'
@@ -214,9 +213,10 @@
   let verb = fromFlagOrDefault Verbosity.normal $ cleanVerbosity flags
 
   -- run 'make clean', which will clean the Omega library if appropriate
-  case mlbi of
-    Just lbi -> rawSystemProgramConf verb makeProgram (withPrograms lbi) ["clean"]
-    Nothing -> return ()
+  pgmConf <- configureProgram verb makeProgram defaultProgramConfiguration
+  makeExists <- doesFileExist "Makefile"
+  when makeExists $
+       rawSystemProgramConf verb makeProgram pgmConf ["clean"]
 
   -- Clean extra files if we don't need to save configuration
   -- (Other temp files are automatically cleaned)