diff --git a/portable/GCC/RISC-V/port.c b/portable/GCC/RISC-V/port.c
index e52fe8b12..8fe7a25d5 100644
--- a/portable/GCC/RISC-V/port.c
+++ b/portable/GCC/RISC-V/port.c
@@ -90,7 +90,7 @@ void vPortSetupTimerInterrupt( void ) __attribute__( ( weak ) );
 uint64_t ullNextTime = 0ULL;
 const uint64_t * pullNextTime = &ullNextTime;
 const size_t uxTimerIncrementsForOneTick = ( size_t ) ( ( configCPU_CLOCK_HZ ) / ( configTICK_RATE_HZ ) ); /* Assumes increment won't go over 32-bits. */
-uint64_t const ullMachineTimerCompareRegisterBase = configMTIMECMP_BASE_ADDRESS;
+UBaseType_t const ullMachineTimerCompareRegisterBase = configMTIMECMP_BASE_ADDRESS;
 volatile uint64_t * pullMachineTimerCompareRegister = NULL;
 
 /* Holds the critical nesting value - deliberately non-zero at start up to
diff --git a/portable/IAR/RISC-V/port.c b/portable/IAR/RISC-V/port.c
index 8040022bd..820423ec5 100644
--- a/portable/IAR/RISC-V/port.c
+++ b/portable/IAR/RISC-V/port.c
@@ -98,7 +98,7 @@ void vPortSetupTimerInterrupt( void ) __attribute__( ( weak ) );
 uint64_t ullNextTime = 0ULL;
 const uint64_t * pullNextTime = &ullNextTime;
 const size_t uxTimerIncrementsForOneTick = ( size_t ) ( ( configCPU_CLOCK_HZ ) / ( configTICK_RATE_HZ ) ); /* Assumes increment won't go over 32-bits. */
-uint64_t const ullMachineTimerCompareRegisterBase = configMTIMECMP_BASE_ADDRESS;
+UBaseType_t const ullMachineTimerCompareRegisterBase = configMTIMECMP_BASE_ADDRESS;
 volatile uint64_t * pullMachineTimerCompareRegister = NULL;
 
 /* Holds the critical nesting value - deliberately non-zero at start up to