diff --git a/src/ethosu_device.c b/src/ethosu_device.c
index ba7e0d5..973caad 100644
--- a/src/ethosu_device.c
+++ b/src/ethosu_device.c
@@ -531,7 +531,7 @@
 uint32_t ethosu_read_reg(struct ethosu_device *dev, uint32_t address)
 {
 #if !defined(ARM_NPU_STUB)
-    ASSERT(dev->base_address != NULL);
+    ASSERT(dev->base_address != 0);
 
     volatile uint32_t *reg = (uint32_t *)(uintptr_t)(dev->base_address + address);
     return *reg;
@@ -546,7 +546,7 @@
 void ethosu_write_reg(struct ethosu_device *dev, uint32_t address, uint32_t value)
 {
 #if !defined(ARM_NPU_STUB)
-    ASSERT(dev->base_address != NULL);
+    ASSERT(dev->base_address != 0);
 
     volatile uint32_t *reg = (uint32_t *)(uintptr_t)(dev->base_address + address);
     *reg                   = value;
diff --git a/src/ethosu_driver.c b/src/ethosu_driver.c
index c640f25..2a2423f 100644
--- a/src/ethosu_driver.c
+++ b/src/ethosu_driver.c
@@ -149,7 +149,7 @@
  ******************************************************************************/
 
 struct ethosu_driver ethosu_drv = {
-    .dev             = {.base_address = NULL, .pmccntr = 0, .pmu_evcntr = {0, 0, 0, 0}, .pmu_evtypr = {0, 0, 0, 0}},
+    .dev             = {.base_address = 0, .pmccntr = 0, .pmu_evcntr = {0, 0, 0, 0}, .pmu_evtypr = {0, 0, 0, 0}},
     .abort_inference = false};
 
 // IRQ
@@ -323,7 +323,7 @@
     ++data_ptr;
 
     // Adjust base address to fast memory area
-    if (ethosu_drv.fast_memory != NULL && num_base_addr >= FAST_MEMORY_BASE_ADDR_INDEX)
+    if (ethosu_drv.fast_memory != 0 && num_base_addr >= FAST_MEMORY_BASE_ADDR_INDEX)
     {
         uint64_t *fast_memory = (uint64_t *)&base_addr[FAST_MEMORY_BASE_ADDR_INDEX];