diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index 88195ab949..fd36425f1a 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -9483,12 +9483,10 @@ static void handle_vec_simd_shli(DisasContext *s, bool is_q, bool insert,
     int immhb = immh << 3 | immb;
     int shift = immhb - (8 << size);
 
-    if (extract32(immh, 3, 1) && !is_q) {
-        unallocated_encoding(s);
-        return;
-    }
+    /* Range of size is limited by decode: immh is a non-zero 4 bit field */
+    assert(size >= 0 && size <= 3);
 
-    if (size > 3 && !is_q) {
+    if (extract32(immh, 3, 1) && !is_q) {
         unallocated_encoding(s);
         return;
     }