diff --git a/lib/compress.js b/lib/compress.js
index ed60ee49..4b0b1272 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -792,8 +792,13 @@ merge(Compressor.prototype, {
                 // Further optimize statement after substitution.
                 stat.reset_opt_flags(compressor);
 
-                compressor.info("Collapsing " + (is_constant ? "constant" : "variable") +
-                    " " + var_name + " [{file}:{line},{col}]", node.start);
+                compressor.info("Collapsing {type} {name} [{file}:{line},{col}]", {
+                    type: is_constant ? "constant" : "variable",
+                    name: var_name,
+                    file: node.start.file,
+                    line: node.start.line,
+                    col: node.start.col
+                });
                 CHANGED = true;
                 return value;
             }