diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index 8d8a4cecb0..eb3a4ab2f0 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -12669,15 +12669,18 @@ static void disas_simd_indexed(DisasContext *s, uint32_t insn)
     case 0x13: /* FCMLA #90 */
     case 0x15: /* FCMLA #180 */
     case 0x17: /* FCMLA #270 */
-        tcg_gen_gvec_3_ptr(vec_full_reg_offset(s, rd),
-                           vec_full_reg_offset(s, rn),
-                           vec_reg_offset(s, rm, index, size), fpst,
-                           is_q ? 16 : 8, vec_full_reg_size(s),
-                           extract32(insn, 13, 2), /* rot */
-                           size == MO_64
-                           ? gen_helper_gvec_fcmlas_idx
-                           : gen_helper_gvec_fcmlah_idx);
-        tcg_temp_free_ptr(fpst);
+        {
+            int rot = extract32(insn, 13, 2);
+            int data = (index << 2) | rot;
+            tcg_gen_gvec_3_ptr(vec_full_reg_offset(s, rd),
+                               vec_full_reg_offset(s, rn),
+                               vec_full_reg_offset(s, rm), fpst,
+                               is_q ? 16 : 8, vec_full_reg_size(s), data,
+                               size == MO_64
+                               ? gen_helper_gvec_fcmlas_idx
+                               : gen_helper_gvec_fcmlah_idx);
+            tcg_temp_free_ptr(fpst);
+        }
         return;
     }
 
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 2a3e4f5d4c..a7a980b1f2 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -7826,26 +7826,42 @@ static int disas_neon_insn_3same_ext(DisasContext *s, uint32_t insn)
 
 static int disas_neon_insn_2reg_scalar_ext(DisasContext *s, uint32_t insn)
 {
-    int rd, rn, rm, rot, size, opr_sz;
+    gen_helper_gvec_3_ptr *fn_gvec_ptr;
+    int rd, rn, rm, opr_sz, data;
     TCGv_ptr fpst;
     bool q;
 
     q = extract32(insn, 6, 1);
     VFP_DREG_D(rd, insn);
     VFP_DREG_N(rn, insn);
-    VFP_DREG_M(rm, insn);
     if ((rd | rn) & q) {
         return 1;
     }
 
     if ((insn & 0xff000f10) == 0xfe000800) {
         /* VCMLA (indexed) -- 1111 1110 S.RR .... .... 1000 ...0 .... */
-        rot = extract32(insn, 20, 2);
-        size = extract32(insn, 23, 1);
-        if (!arm_dc_feature(s, ARM_FEATURE_V8_FCMA)
-            || (!size && !arm_dc_feature(s, ARM_FEATURE_V8_FP16))) {
+        int rot = extract32(insn, 20, 2);
+        int size = extract32(insn, 23, 1);
+        int index;
+
+        if (!arm_dc_feature(s, ARM_FEATURE_V8_FCMA)) {
             return 1;
         }
+        if (size == 0) {
+            if (!arm_dc_feature(s, ARM_FEATURE_V8_FP16)) {
+                return 1;
+            }
+            /* For fp16, rm is just Vm, and index is M.  */
+            rm = extract32(insn, 0, 4);
+            index = extract32(insn, 5, 1);
+        } else {
+            /* For fp32, rm is the usual M:Vm, and index is 0.  */
+            VFP_DREG_M(rm, insn);
+            index = 0;
+        }
+        data = (index << 2) | rot;
+        fn_gvec_ptr = (size ? gen_helper_gvec_fcmlas_idx
+                       : gen_helper_gvec_fcmlah_idx);
     } else {
         return 1;
     }
@@ -7864,9 +7880,7 @@ static int disas_neon_insn_2reg_scalar_ext(DisasContext *s, uint32_t insn)
     tcg_gen_gvec_3_ptr(vfp_reg_offset(1, rd),
                        vfp_reg_offset(1, rn),
                        vfp_reg_offset(1, rm), fpst,
-                       opr_sz, opr_sz, rot,
-                       size ? gen_helper_gvec_fcmlas_idx
-                       : gen_helper_gvec_fcmlah_idx);
+                       opr_sz, opr_sz, data, fn_gvec_ptr);
     tcg_temp_free_ptr(fpst);
     return 0;
 }
diff --git a/target/arm/vec_helper.c b/target/arm/vec_helper.c
index 073e5c58e7..8f2dc4b989 100644
--- a/target/arm/vec_helper.c
+++ b/target/arm/vec_helper.c
@@ -317,10 +317,11 @@ void HELPER(gvec_fcmlah_idx)(void *vd, void *vn, void *vm,
     float_status *fpst = vfpst;
     intptr_t flip = extract32(desc, SIMD_DATA_SHIFT, 1);
     uint32_t neg_imag = extract32(desc, SIMD_DATA_SHIFT + 1, 1);
+    intptr_t index = extract32(desc, SIMD_DATA_SHIFT + 2, 2);
     uint32_t neg_real = flip ^ neg_imag;
     uintptr_t i;
-    float16 e1 = m[H2(flip)];
-    float16 e3 = m[H2(1 - flip)];
+    float16 e1 = m[H2(2 * index + flip)];
+    float16 e3 = m[H2(2 * index + 1 - flip)];
 
     /* Shift boolean to the sign bit so we can xor to negate.  */
     neg_real <<= 15;
@@ -377,10 +378,11 @@ void HELPER(gvec_fcmlas_idx)(void *vd, void *vn, void *vm,
     float_status *fpst = vfpst;
     intptr_t flip = extract32(desc, SIMD_DATA_SHIFT, 1);
     uint32_t neg_imag = extract32(desc, SIMD_DATA_SHIFT + 1, 1);
+    intptr_t index = extract32(desc, SIMD_DATA_SHIFT + 2, 2);
     uint32_t neg_real = flip ^ neg_imag;
     uintptr_t i;
-    float32 e1 = m[H4(flip)];
-    float32 e3 = m[H4(1 - flip)];
+    float32 e1 = m[H4(2 * index + flip)];
+    float32 e3 = m[H4(2 * index + 1 - flip)];
 
     /* Shift boolean to the sign bit so we can xor to negate.  */
     neg_real <<= 31;
