diff --git a/components/bootloader/subproject/main/bootloader_start.c b/components/bootloader/subproject/main/bootloader_start.c
index eed030984..9cdddf4c6 100644
--- a/components/bootloader/subproject/main/bootloader_start.c
+++ b/components/bootloader/subproject/main/bootloader_start.c
@@ -599,6 +599,7 @@ static void set_cache_and_start_app(
     uint32_t irom_size,
     uint32_t entry_addr)
 {
+    int rc;
     ESP_LOGD(TAG, "configure drom and irom and start");
     Cache_Read_Disable( 0 );
     Cache_Flush( 0 );
@@ -610,20 +611,34 @@ static void set_cache_and_start_app(
         DPORT_PRO_FLASH_MMU_TABLE[i] = DPORT_FLASH_MMU_TABLE_INVALID_VAL;
     }
 
-    uint32_t drom_page_count = (drom_size + 64*1024 - 1) / (64*1024); // round up to 64k
-    ESP_LOGV(TAG, "d mmu set paddr=%08x vaddr=%08x size=%d n=%d", drom_addr & 0xffff0000, drom_load_addr & 0xffff0000, drom_size, drom_page_count );
-    int rc = cache_flash_mmu_set( 0, 0, drom_load_addr & 0xffff0000, drom_addr & 0xffff0000, 64, drom_page_count );
-    ESP_LOGV(TAG, "rc=%d", rc );
-    rc = cache_flash_mmu_set( 1, 0, drom_load_addr & 0xffff0000, drom_addr & 0xffff0000, 64, drom_page_count );
-    ESP_LOGV(TAG, "rc=%d", rc );
-    uint32_t irom_page_count = (irom_size + 64*1024 - 1) / (64*1024); // round up to 64k
-    ESP_LOGV(TAG, "i mmu set paddr=%08x vaddr=%08x size=%d n=%d", irom_addr & 0xffff0000, irom_load_addr & 0xffff0000, irom_size, irom_page_count );
-    rc = cache_flash_mmu_set( 0, 0, irom_load_addr & 0xffff0000, irom_addr & 0xffff0000, 64, irom_page_count );
-    ESP_LOGV(TAG, "rc=%d", rc );
-    rc = cache_flash_mmu_set( 1, 0, irom_load_addr & 0xffff0000, irom_addr & 0xffff0000, 64, irom_page_count );
-    ESP_LOGV(TAG, "rc=%d", rc );
-    DPORT_REG_CLR_BIT( DPORT_PRO_CACHE_CTRL1_REG, (DPORT_PRO_CACHE_MASK_IRAM0) | (DPORT_PRO_CACHE_MASK_IRAM1 & 0) | (DPORT_PRO_CACHE_MASK_IROM0 & 0) | DPORT_PRO_CACHE_MASK_DROM0 | DPORT_PRO_CACHE_MASK_DRAM1 );
-    DPORT_REG_CLR_BIT( DPORT_APP_CACHE_CTRL1_REG, (DPORT_APP_CACHE_MASK_IRAM0) | (DPORT_APP_CACHE_MASK_IRAM1 & 0) | (DPORT_APP_CACHE_MASK_IROM0 & 0) | DPORT_APP_CACHE_MASK_DROM0 | DPORT_APP_CACHE_MASK_DRAM1 );
+    uint32_t drom_load_addr_aligned = drom_load_addr & MMU_FLASH_MASK;
+    uint32_t drom_page_count = bootloader_cache_pages_to_map(drom_size, drom_load_addr);
+    ESP_LOGV(TAG, "d mmu set paddr=%08x vaddr=%08x size=%d n=%d",
+            drom_addr & MMU_FLASH_MASK, drom_load_addr_aligned, drom_size, drom_page_count);
+    rc = cache_flash_mmu_set(0, 0, drom_load_addr_aligned, drom_addr & MMU_FLASH_MASK, 64, drom_page_count);
+    ESP_LOGV(TAG, "rc=%d", rc);
+    rc = cache_flash_mmu_set(1, 0, drom_load_addr_aligned, drom_addr & MMU_FLASH_MASK, 64, drom_page_count);
+    ESP_LOGV(TAG, "rc=%d", rc);
+
+    uint32_t irom_load_addr_aligned = irom_load_addr & MMU_FLASH_MASK;
+    uint32_t irom_page_count = bootloader_cache_pages_to_map(irom_size, irom_load_addr);
+    ESP_LOGV(TAG, "i mmu set paddr=%08x vaddr=%08x size=%d n=%d",
+            irom_addr & MMU_FLASH_MASK, irom_load_addr_aligned, irom_size, irom_page_count);
+    rc = cache_flash_mmu_set(0, 0, irom_load_addr_aligned, irom_addr & MMU_FLASH_MASK, 64, irom_page_count);
+    ESP_LOGV(TAG, "rc=%d", rc);
+    rc = cache_flash_mmu_set(1, 0, irom_load_addr_aligned, irom_addr & MMU_FLASH_MASK, 64, irom_page_count);
+    ESP_LOGV(TAG, "rc=%d", rc);
+
+    DPORT_REG_CLR_BIT( DPORT_PRO_CACHE_CTRL1_REG,
+            (DPORT_PRO_CACHE_MASK_IRAM0) | (DPORT_PRO_CACHE_MASK_IRAM1 & 0) |
+            (DPORT_PRO_CACHE_MASK_IROM0 & 0) | DPORT_PRO_CACHE_MASK_DROM0 |
+            DPORT_PRO_CACHE_MASK_DRAM1 );
+
+    DPORT_REG_CLR_BIT( DPORT_APP_CACHE_CTRL1_REG,
+            (DPORT_APP_CACHE_MASK_IRAM0) | (DPORT_APP_CACHE_MASK_IRAM1 & 0) |
+            (DPORT_APP_CACHE_MASK_IROM0 & 0) | DPORT_APP_CACHE_MASK_DROM0 |
+            DPORT_APP_CACHE_MASK_DRAM1 );
+
     Cache_Read_Enable( 0 );
 
     // Application will need to do Cache_Flush(1) and Cache_Read_Enable(1)
diff --git a/components/bootloader_support/include_priv/bootloader_flash.h b/components/bootloader_support/include_priv/bootloader_flash.h
index 763136e03..9f19b4b69 100644
--- a/components/bootloader_support/include_priv/bootloader_flash.h
+++ b/components/bootloader_support/include_priv/bootloader_flash.h
@@ -100,4 +100,21 @@ esp_err_t bootloader_flash_write(size_t dest_addr, void *src, size_t size, bool
  */
 esp_err_t bootloader_flash_erase_sector(size_t sector);
 
+/* Cache MMU block size */
+#define MMU_BLOCK_SIZE    0x00010000
+
+/* Cache MMU address mask (MMU tables ignore bits which are zero) */
+#define MMU_FLASH_MASK    (~(MMU_BLOCK_SIZE - 1))
+
+/**
+ * @brief Calculate the number of cache pages to map
+ * @param size  size of data to map
+ * @param vaddr  virtual address where data will be mapped
+ * @return number of cache MMU pages required to do the mapping
+ */
+static inline uint32_t bootloader_cache_pages_to_map(uint32_t size, uint32_t vaddr)
+{
+    return (size + (vaddr - (vaddr & MMU_FLASH_MASK)) + MMU_BLOCK_SIZE - 1) / MMU_BLOCK_SIZE;
+}
+
 #endif
diff --git a/components/bootloader_support/src/bootloader_flash.c b/components/bootloader_support/src/bootloader_flash.c
index a7a6f6e61..1c45890f0 100644
--- a/components/bootloader_support/src/bootloader_flash.c
+++ b/components/bootloader_support/src/bootloader_flash.c
@@ -86,8 +86,6 @@ static const char *TAG = "bootloader_flash";
 */
 #define MMU_BLOCK0_VADDR  0x3f400000
 #define MMU_BLOCK50_VADDR 0x3f720000
-#define MMU_FLASH_MASK    0xffff0000
-#define MMU_BLOCK_SIZE    0x00010000
 
 static bool mapped;
 
@@ -107,10 +105,11 @@ const void *bootloader_mmap(uint32_t src_addr, uint32_t size)
     }
 
     uint32_t src_addr_aligned = src_addr & MMU_FLASH_MASK;
-    uint32_t count = (size + (src_addr - src_addr_aligned) + 0xffff) / MMU_BLOCK_SIZE;
+    uint32_t count = bootloader_cache_pages_to_map(size, src_addr);
     Cache_Read_Disable(0);
     Cache_Flush(0);
-    ESP_LOGD(TAG, "mmu set paddr=%08x count=%d", src_addr_aligned, count );
+    ESP_LOGD(TAG, "mmu set paddr=%08x count=%d size=%x src_addr=%x src_addr_aligned=%x",
+            src_addr & MMU_FLASH_MASK, count, size, src_addr, src_addr_aligned );
     int e = cache_flash_mmu_set(0, 0, MMU_BLOCK0_VADDR, src_addr_aligned, 64, count);
     if (e != 0) {
         ESP_LOGE(TAG, "cache_flash_mmu_set failed: %d\n", e);