diff --git a/plat/arm/common/aarch64/arm_pauth.c b/plat/arm/common/aarch64/arm_pauth.c
index a685c31..7cea8a0 100644
--- a/plat/arm/common/aarch64/arm_pauth.c
+++ b/plat/arm/common/aarch64/arm_pauth.c
@@ -4,27 +4,25 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
+#include <arch_helpers.h>
 #include <cdefs.h>
 #include <stdint.h>
 
 /*
- * Instruction pointer authentication key A. The low 64-bit are at [0], and the
- * high bits at [1].
+ * This is only a toy implementation to generate a seemingly random
+ * 128-bit key from sp, x30 and cntpct_el0 values.
+ * A production system must re-implement this function to generate
+ * keys from a reliable randomness source.
  */
-uint64_t plat_apiakey[2];
-
-/*
- * This is only a toy implementation to generate a seemingly random 128-bit key
- * from sp and x30 values. A production system must re-implement this function
- * to generate keys from a reliable randomness source.
- */
-uint64_t *plat_init_apiakey(void)
+uint128_t plat_init_apkey(void)
 {
-	uintptr_t return_addr = (uintptr_t)__builtin_return_address(0U);
-	uintptr_t frame_addr = (uintptr_t)__builtin_frame_address(0U);
+	uint64_t return_addr = (uint64_t)__builtin_return_address(0U);
+	uint64_t frame_addr = (uint64_t)__builtin_frame_address(0U);
+	uint64_t cntpct = read_cntpct_el0();
 
-	plat_apiakey[0] = (return_addr << 13) ^ frame_addr;
-	plat_apiakey[1] = (frame_addr << 15) ^ return_addr;
+	/* Generate 128-bit key */
+	uint64_t key_lo = (return_addr << 13) ^ frame_addr ^ cntpct;
+	uint64_t key_hi = (frame_addr << 15) ^ return_addr ^ cntpct;
 
-	return plat_apiakey;
+	return ((uint128_t)(key_hi) << 64) | key_lo;
 }