diff --git a/cranelift/filetests/preopt/simplify.cton b/cranelift/filetests/preopt/simplify.cton
index a2e67caf31..020e2f0108 100644
--- a/cranelift/filetests/preopt/simplify.cton
+++ b/cranelift/filetests/preopt/simplify.cton
@@ -75,6 +75,6 @@ ebb0(v0: i32):
 ; sameln: function %irsub_imm
 ; nextln: ebb0(v0: i32):
 ; nextln:     v1 = iconst.i32 2
-; nextln:     v2 = irsub_imm v1, 2
+; nextln:     v2 = irsub_imm v0, 2
 ; nextln:     return v2
 ; nextln: }
diff --git a/lib/cretonne/src/preopt.rs b/lib/cretonne/src/preopt.rs
index bdd1c445eb..0a1c13d6ea 100644
--- a/lib/cretonne/src/preopt.rs
+++ b/lib/cretonne/src/preopt.rs
@@ -505,7 +505,7 @@ fn simplify(pos: &mut FuncCursor, inst: Inst) {
                         new_opcode,
                         ty,
                         imm,
-                        args[0],
+                        args[1],
                     );
                 }
             }