diff --git a/cranelift/filetests/postopt/fold_offset_into_address.clif b/cranelift/filetests/postopt/fold_offset_into_address.clif
index 45ce7bcd0a..52379f4a50 100644
--- a/cranelift/filetests/postopt/fold_offset_into_address.clif
+++ b/cranelift/filetests/postopt/fold_offset_into_address.clif
@@ -16,3 +16,17 @@ ebb0(v0: i64):
 ; nextln: [RexOp1ldDisp8#808b]                v2 = load.i64 notrap aligned v0+16
 ; nextln: [Op1ret#c3]                         return v2
 ; nextln: }
+
+function u0:1(i64, i64 vmctx) {
+ebb0(v3: i64, v0: i64):
+                     v1 = iadd_imm.i64 v0, 16
+[RexOp1stDisp8#8089] store.i64 notrap aligned v3, v1
+[Op1ret#c3]          return
+}
+
+; sameln: function u0:1(i64, i64 vmctx) fast {
+; nextln: ebb0(v3: i64, v0: i64):
+; nextln:                                     v1 = iadd_imm v0, 16
+; nextln: [RexOp1stDisp8#8089]                store notrap aligned v3, v0+16
+; nextln: [Op1ret#c3]                         return
+; nextln: }
diff --git a/lib/codegen/src/postopt.rs b/lib/codegen/src/postopt.rs
index 8c64b9bb04..a57497b331 100644
--- a/lib/codegen/src/postopt.rs
+++ b/lib/codegen/src/postopt.rs
@@ -329,7 +329,7 @@ fn optimize_complex_addresses(pos: &mut EncCursor, inst: Inst, isa: &TargetIsa)
                     ..
                 } => {
                     if let Some(imm) = offset.try_add_i64(imm.into()) {
-                        store_args[0] = arg;
+                        store_args[1] = arg;
                         *offset = imm;
                     } else {
                         // Overflow.