Fixes #1772

2 files changed, 27 insertions, 2 deletions

diff --git a/src/js_parser.zig b/src/js_parser.zig
index 1fa86041f..1dbf1ebf9 100644
--- a/src/js_parser.zig
+++ b/src/js_parser.zig
@@ -117,8 +117,9 @@ fn foldStringAddition(lhs: Expr, rhs: Expr) ?Expr {
     switch (lhs.data) {
         .e_string => |left| {
             if (rhs.data == .e_string and left.isUTF8() and rhs.data.e_string.isUTF8()) {
-                lhs.data.e_string.push(rhs.data.e_string);
-                return lhs;
+                var orig = lhs.data.e_string.*;
+                orig.push(rhs.data.e_string);
+                return Expr.init(E.String, orig, lhs.loc);
             }
         },
         .e_binary => |bin| {
diff --git a/test/bun.js/transpiler.test.js b/test/bun.js/transpiler.test.js
index bc7102b95..94c3d52d2 100644
--- a/test/bun.js/transpiler.test.js
+++ b/test/bun.js/transpiler.test.js
@@ -915,6 +915,19 @@ export var ComponentThatHasSpreadCausesDeopt = $jsx(Hello, {
 
     it("fold string addition", () => {
       expectPrinted_(
+        `
+const a = "[^aeiou]";
+const b = a + "[^aeiouy]*";
+console.log(a);
+        `,
+        `
+const a = "[^aeiou]";
+const b = a + "[^aeiouy]*";
+console.log(a)
+        `.trim(),
+      );
+
+      expectPrinted_(
         `export const foo = "a" + "b";`,
         `export const foo = "ab"`,
       );
@@ -1734,6 +1747,17 @@ class Foo {
         `return "foobar";`,
       );
 
+      check(
+        `
+const a = "[^aeiou]";
+const b = a + "[^aeiouy]*";
+console.log(a, b);
+        `,
+        `
+console.log("[^aeiou]", "[^aeiou][^aeiouy]*");
+        `.trim(),
+      );
+
       // check that it doesn't inline after "var"
       check(
         `