diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index 036212b5f4..7fdf2357c0 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -819,7 +819,7 @@ pub fn (mut f Fmt) expr(node ast.Expr) {
 		ast.ConcatExpr {
 			for i, val in node.vals {
 				if i != 0 {
-					f.write(' + ')
+					f.write(', ')
 				}
 				f.expr(val)
 			}
diff --git a/vlib/v/fmt/tests/assign_keep.vv b/vlib/v/fmt/tests/assign_keep.vv
new file mode 100644
index 0000000000..230d3a8bd4
--- /dev/null
+++ b/vlib/v/fmt/tests/assign_keep.vv
@@ -0,0 +1,3 @@
+a, b := if true { 'a', 'b' } else { 'b', 'a' }
+println(a)
+println(b)