diff --git a/lib/compress.js b/lib/compress.js
index e9591590..7f3574de 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1288,7 +1288,7 @@ merge(Compressor.prototype, {
         }
 
         def(AST_Call, function(compressor){
-            if (has_pure_annotation(this)) {
+            if (compressor.option("side_effects") && has_pure_annotation(this)) {
                 compressor.warn("Dropping __PURE__ call [{file}:{line},{col}]", this.start);
                 return false;
             }