diff --git a/testbench/tests/pmp_random/main.c b/testbench/tests/pmp_random/main.c
index 327c1478238..2fb11817525 100644
--- a/testbench/tests/pmp_random/main.c
+++ b/testbench/tests/pmp_random/main.c
@@ -230,6 +230,7 @@ uint32_t generate_napot_mask(uint32_t value) {
 int get_effective_range(uint32_t *address, enum RegionType region_type, uint32_t **addr_hi, uint32_t **addr_lo){
     *address = legalize_address(*address, region_type);
 
+    uint32_t mask = generate_napot_mask(*address);
     switch (region_type) {
     case OFF:
         *addr_lo = 0;
@@ -244,7 +245,6 @@ int get_effective_range(uint32_t *address, enum RegionType region_type, uint32_t
         *addr_hi = *addr_lo + 1;
         break;
     case NAPOT:
-        uint32_t mask = generate_napot_mask(*address);
         *addr_lo = ((uint32_t)address & ~mask) << 2;
         *addr_hi = *addr_lo + (1 << trailing_ones(*address));
         break;