diff --git a/lib/compress.js b/lib/compress.js
index 831050c9ef..9e0610cc42 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -12270,7 +12270,7 @@ Compressor.prototype.compress = function(node) {
                     return maintain_this_binding(parent, compressor.self(), self.left).optimize(compressor);
                 } else if (!(ll instanceof AST_Node)) {
                     AST_Node.warn("Condition left of && always true [{start}]", self);
-                    return make_sequence(self, [ self.left, self.right ]).optimize(compressor);
+                    return make_sequence(self, [ self.left.clone(), self.right ]).optimize(compressor);
                 }
                 if (!self.right.evaluate(compressor, true)) {
                     if (in_bool && !(self.right.evaluate(compressor) instanceof AST_Node)) {
diff --git a/test/compress/evaluate.js b/test/compress/evaluate.js
index eb8a0583b8..0c1dcccaaf 100644
--- a/test/compress/evaluate.js
+++ b/test/compress/evaluate.js
@@ -3416,3 +3416,26 @@ issue_5558: {
     }
     expect_stdout: "100"
 }
+
+issue_5940: {
+    options = {
+        conditionals: true,
+        evaluate: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        (function f(a) {
+            f && (console, 42) && (f && (a = [])) && console.log("PASS");
+            f = 42;
+        })();
+    }
+    expect: {
+        (function f(a) {
+            f && (console, 42) && (f && []) && console.log("PASS"),
+            f = 42;
+        })();
+    }
+    expect_stdout: "PASS"
+}