diff --git a/lib/psci/psci_mem_protect.c b/lib/psci/psci_mem_protect.c
index fca84e9..857146b 100644
--- a/lib/psci/psci_mem_protect.c
+++ b/lib/psci/psci_mem_protect.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,30 +9,31 @@
 #include <utils.h>
 #include "psci_private.h"
 
-int psci_mem_protect(unsigned int enable)
+u_register_t psci_mem_protect(unsigned int enable)
 {
 	int val;
 
-	assert(psci_plat_pm_ops->read_mem_protect);
-	assert(psci_plat_pm_ops->write_mem_protect);
+	assert(psci_plat_pm_ops->read_mem_protect != NULL);
+	assert(psci_plat_pm_ops->write_mem_protect != NULL);
 
 	if (psci_plat_pm_ops->read_mem_protect(&val) < 0)
-		return PSCI_E_NOT_SUPPORTED;
+		return (u_register_t) PSCI_E_NOT_SUPPORTED;
 	if (psci_plat_pm_ops->write_mem_protect(enable) < 0)
-		return PSCI_E_NOT_SUPPORTED;
+		return (u_register_t) PSCI_E_NOT_SUPPORTED;
 
-	return val != 0;
+	return (val != 0) ? 1U : 0U;
 }
 
-int psci_mem_chk_range(uintptr_t base, u_register_t length)
+u_register_t psci_mem_chk_range(uintptr_t base, u_register_t length)
 {
 	int ret;
 
-	assert(psci_plat_pm_ops->mem_protect_chk);
+	assert(psci_plat_pm_ops->mem_protect_chk != NULL);
 
-	if (length == 0 || check_uptr_overflow(base, length-1))
-		return PSCI_E_DENIED;
+	if ((length == 0U) || check_uptr_overflow(base, length - 1U))
+		return (u_register_t) PSCI_E_DENIED;
 
 	ret = psci_plat_pm_ops->mem_protect_chk(base, length);
-	return (ret < 0) ? PSCI_E_DENIED : PSCI_E_SUCCESS;
+	return (ret < 0) ?
+	       (u_register_t) PSCI_E_DENIED : (u_register_t) PSCI_E_SUCCESS;
 }
diff --git a/lib/psci/psci_private.h b/lib/psci/psci_private.h
index ac99876..75f7d45 100644
--- a/lib/psci/psci_private.h
+++ b/lib/psci/psci_private.h
@@ -330,7 +330,7 @@
 			unsigned int power_state);
 
 /* Private exported functions from psci_mem_protect.c */
-int psci_mem_protect(unsigned int enable);
-int psci_mem_chk_range(uintptr_t base, u_register_t length);
+u_register_t psci_mem_protect(unsigned int enable);
+u_register_t psci_mem_chk_range(uintptr_t base, u_register_t length);
 
 #endif /* PSCI_PRIVATE_H */