diff --git a/simd/arm/jquanti-neon.c b/simd/arm/jquanti-neon.c
index a7eb6f1..d5d95d8 100644
--- a/simd/arm/jquanti-neon.c
+++ b/simd/arm/jquanti-neon.c
@@ -1,7 +1,7 @@
 /*
  * jquanti-neon.c - sample data conversion and quantization (Arm Neon)
  *
- * Copyright (C) 2020, Arm Limited.  All Rights Reserved.
+ * Copyright (C) 2020-2021, Arm Limited.  All Rights Reserved.
  *
  * This software is provided 'as-is', without any express or implied
  * warranty.  In no event will the authors be held liable for any damages
@@ -100,6 +100,9 @@
   DCTELEM *shift_ptr = divisors + 3 * DCTSIZE2;
   int i;
 
+#if defined(__clang__) && (defined(__aarch64__) || defined(_M_ARM64))
+#pragma unroll
+#endif
   for (i = 0; i < DCTSIZE; i += DCTSIZE / 2) {
     /* Load DCT coefficients. */
     int16x8_t row0 = vld1q_s16(workspace + (i + 0) * DCTSIZE);