diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index fa60cf908f8f703ead14f5c0caef040d667b6665..f4e2afa72c246f3a9246ef6ac370adeb8d3972a4 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -7405,13 +7405,26 @@ static void handle_simd_shift_intfp_conv(DisasContext *s, bool is_scalar,
                                          int immh, int immb, int opcode,
                                          int rn, int rd)
 {
-    bool is_double = extract32(immh, 3, 1);
-    int size = is_double ? MO_64 : MO_32;
-    int elements;
+    int size, elements, fracbits;
     int immhb = immh << 3 | immb;
-    int fracbits = (is_double ? 128 : 64) - immhb;
 
-    if (!extract32(immh, 2, 2)) {
+    if (immh & 8) {
+        size = MO_64;
+        if (!is_scalar && !is_q) {
+            unallocated_encoding(s);
+            return;
+        }
+    } else if (immh & 4) {
+        size = MO_32;
+    } else if (immh & 2) {
+        size = MO_16;
+        if (!arm_dc_feature(s, ARM_FEATURE_V8_FP16)) {
+            unallocated_encoding(s);
+            return;
+        }
+    } else {
+        /* immh == 0 would be a failure of the decode logic */
+        g_assert(immh == 1);
         unallocated_encoding(s);
         return;
     }
@@ -7419,20 +7432,14 @@ static void handle_simd_shift_intfp_conv(DisasContext *s, bool is_scalar,
     if (is_scalar) {
         elements = 1;
     } else {
-        elements = is_double ? 2 : is_q ? 4 : 2;
-        if (is_double && !is_q) {
-            unallocated_encoding(s);
-            return;
-        }
+        elements = (8 << is_q) >> size;
     }
+    fracbits = (16 << size) - immhb;
 
     if (!fp_access_check(s)) {
         return;
     }
 
-    /* immh == 0 would be a failure of the decode logic */
-    g_assert(immh);
-
     handle_simd_intfp_conv(s, rd, rn, elements, !is_u, fracbits, size);
 }