diff --git a/lib/compress.js b/lib/compress.js
index 4152bd06..527b8e62 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -190,7 +190,7 @@ merge(Compressor.prototype, {
             if ((1 / val) < 0) {
                 return make_node(AST_UnaryPrefix, orig, {
                     operator: "-",
-                    expression: make_node(AST_Number, null, { value: -val })
+                    expression: make_node(AST_Number, orig, { value: -val })
                 });
             }