diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -34,7 +34,7 @@
 
 ```bash
 cabal update
-cabal install --overwrite-policy=always phino-0.0.77
+cabal install --overwrite-policy=always phino-0.0.78
 phino --version
 ```
 
@@ -419,55 +419,55 @@
 === parse/phi ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      1453423.801 μs
-  avg:        145342.380 μs
-  min:        132303.541 μs
-  max:        180063.070 μs
-  std dev:    17728.265 μs
+  total:      1440313.041 μs
+  avg:        144031.304 μs
+  min:        129401.716 μs
+  max:        176360.645 μs
+  std dev:    17903.429 μs
 === parse/xmir ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      7722131.410 μs
-  avg:        772213.141 μs
-  min:        693107.857 μs
-  max:        828732.420 μs
-  std dev:    38785.881 μs
+  total:      7726130.473 μs
+  avg:        772613.047 μs
+  min:        698264.764 μs
+  max:        823731.966 μs
+  std dev:    37463.636 μs
 === rewrite/normalize ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      639905.274 μs
-  avg:        63990.527 μs
-  min:        45971.308 μs
-  max:        73170.128 μs
-  std dev:    7936.545 μs
+  total:      354506.194 μs
+  avg:        35450.619 μs
+  min:        35028.708 μs
+  max:        36155.099 μs
+  std dev:    348.991 μs
 === print/sweet/multiline ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      4161166.958 μs
-  avg:        416116.696 μs
-  min:        396490.037 μs
-  max:        440928.823 μs
-  std dev:    13277.332 μs
+  total:      3996044.953 μs
+  avg:        399604.495 μs
+  min:        380451.516 μs
+  max:        426315.460 μs
+  std dev:    12846.211 μs
 === print/sweet/flat ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      4101875.046 μs
-  avg:        410187.505 μs
-  min:        389712.342 μs
-  max:        421958.218 μs
-  std dev:    11340.723 μs
+  total:      3922886.214 μs
+  avg:        392288.621 μs
+  min:        359335.839 μs
+  max:        413380.865 μs
+  std dev:    17623.494 μs
 === print/salty/multiline ===
   warmup:     3 iterations
   batches:    10 x 1
-  total:      14145704.886 μs
-  avg:        1414570.489 μs
-  min:        1375850.741 μs
-  max:        1454788.955 μs
-  std dev:    27864.927 μs
+  total:      13752970.922 μs
+  avg:        1375297.092 μs
+  min:        1346097.350 μs
+  max:        1437457.343 μs
+  std dev:    32845.881 μs
 ```
 
 The results were calculated in [this GHA job][benchmark-gha]
-on 2026-06-10 at 14:25,
+on 2026-06-11 at 08:27,
 on Linux with 4 CPUs.
 
 <!-- benchmark_end -->
@@ -503,4 +503,4 @@
 [jna]: https://github.com/java-native-access/jna
 [jna-native]: https://github.com/java-native-access/jna/blob/master/src/com/sun/jna/Native.java
 [jeo]: https://github.com/objectionary/jeo-maven-plugin
-[benchmark-gha]: https://github.com/objectionary/phino/actions/runs/27282978502
+[benchmark-gha]: https://github.com/objectionary/phino/actions/runs/27333912876
diff --git a/phino.cabal b/phino.cabal
--- a/phino.cabal
+++ b/phino.cabal
@@ -1,6 +1,6 @@
 cabal-version: 3.0
 name: phino
-version: 0.0.78
+version: 0.0.79
 license: MIT
 synopsis: Command-Line Manipulator of 𝜑-Calculus Expressions
 description: Please see the README on GitHub at <https://github.com/objectionary/phino#readme>
diff --git a/src/Misc.hs b/src/Misc.hs
--- a/src/Misc.hs
+++ b/src/Misc.hs
@@ -310,6 +310,8 @@
 -- Right Infinity
 -- >>> btsToNum (BtMany ["FF", "F0", "00", "00", "00", "00", "00", "00"])
 -- Right (-Infinity)
+-- >>> btsToNum (BtMany ["80", "00", "00", "00", "00", "00", "00", "00"])
+-- Right (-0.0)
 btsToNum :: Bytes -> Either Int Double
 btsToNum hx =
   let bytes = btsToWord8 hx
@@ -318,7 +320,7 @@
         else
           let word = toWord64BE bytes
               val = wordToDouble word
-           in if isNaN val || isInfinite val
+           in if isNaN val || isInfinite val || isNegativeZero val
                 then Right val
                 else case properFraction val of
                   (n, 0.0) -> Left n
diff --git a/src/Parser.hs b/src/Parser.hs
--- a/src/Parser.hs
+++ b/src/Parser.hs
@@ -177,11 +177,12 @@
   return
     ( DataNumber
         ( numToBts
-            ( toRealFloat
-                ( case sign of
-                    Just '-' -> negate unsigned
-                    _ -> unsigned
-                )
+            ( case sign of
+                -- Negate the Double rather than the Scientific so that a zero
+                -- literal preserves its sign: Scientific has no negative zero,
+                -- but negate on Double yields -0.0, a distinct IEEE-754 value.
+                Just '-' -> negate (toRealFloat unsigned)
+                _ -> toRealFloat unsigned
             )
         )
     )
diff --git a/test/ParserSpec.hs b/test/ParserSpec.hs
--- a/test/ParserSpec.hs
+++ b/test/ParserSpec.hs
@@ -356,6 +356,9 @@
     test
       parseNumber
       [ ("0", Just (DataNumber (BtMany ["00", "00", "00", "00", "00", "00", "00", "00"])))
+      , ("-0", Just (DataNumber (BtMany ["80", "00", "00", "00", "00", "00", "00", "00"])))
+      , ("-0.0", Just (DataNumber (BtMany ["80", "00", "00", "00", "00", "00", "00", "00"])))
+      , ("+0", Just (DataNumber (BtMany ["00", "00", "00", "00", "00", "00", "00", "00"])))
       , ("1", Just (DataNumber (BtMany ["3F", "F0", "00", "00", "00", "00", "00", "00"])))
       , ("-1", Just (DataNumber (BtMany ["BF", "F0", "00", "00", "00", "00", "00", "00"])))
       , ("+1", Just (DataNumber (BtMany ["3F", "F0", "00", "00", "00", "00", "00", "00"])))