--- 
+++ 
@@ -24,7 +24,7 @@
     // x--4 (which is a syntax error).
     char prev = getLastChar();
     boolean negativeZero = isNegativeZero(x);
-    if (x < 0 && prev == '-') {
+    if (x < 0 && prev == '-' || isNegativeZero(x) && prev == '-') {
       add(" ");
     }