diff --git a/lib/compress.js b/lib/compress.js
index 3dcb922a..9c2dcbba 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -978,9 +978,7 @@ merge(Compressor.prototype, {
                 || this.alternative.has_side_effects(compressor);
         });
         def(AST_Unary, function(compressor){
-            return this.operator == "delete"
-                || this.operator == "++"
-                || this.operator == "--"
+            return member(this.operator, ["delete", "++", "--", "yield", "yield*"])
                 || this.expression.has_side_effects(compressor);
         });
         def(AST_SymbolRef, function(compressor){
diff --git a/test/compress/issue-1043.js b/test/compress/issue-1043.js
new file mode 100644
index 00000000..78043f65
--- /dev/null
+++ b/test/compress/issue-1043.js
@@ -0,0 +1,30 @@
+issue_1043: {
+    options = {
+        side_effects: true
+    };
+
+    input: {
+        function* range(start = 0, end = null, step = 1) {
+            if (end == null) {
+                end = start;
+                start = 0;
+            }
+
+            for (let i = start; i < end; i += step) {
+                yield i;
+            }
+        }
+    }
+
+    expect: {
+        function* range(start = 0, end = null, step = 1) {
+            if (null == end) {
+                end = start;
+                start = 0;
+            }
+
+            for (let i = start; i < end; i += step)
+                yield i;
+        }
+    }
+}