diff --git a/qemu/target/arm/translate-a64.c b/qemu/target/arm/translate-a64.c
index 7d308e41..3e3263b1 100644
--- a/qemu/target/arm/translate-a64.c
+++ b/qemu/target/arm/translate-a64.c
@@ -7683,7 +7683,7 @@ static void handle_simd_dupe(DisasContext *s, int is_q, int rd, int rn,
 {
     TCGContext *tcg_ctx = s->uc->tcg_ctx;
     int size = ctz32(imm5);
-    int index = imm5 >> (size + 1);
+    int index;
 
     if (size > 3 || (size == 3 && !is_q)) {
         unallocated_encoding(s);
@@ -7694,6 +7694,7 @@ static void handle_simd_dupe(DisasContext *s, int is_q, int rd, int rn,
         return;
     }
 
+    index = imm5 >> (size + 1);
     tcg_gen_gvec_dup_mem(tcg_ctx, size, vec_full_reg_offset(s, rd),
                          vec_reg_offset(s, rn, index, size),
                          is_q ? 16 : 8, vec_full_reg_size(s));