diff --git a/Tools/AP_Bootloader/bl_protocol.cpp b/Tools/AP_Bootloader/bl_protocol.cpp
index 7ce33dbdc2..1dae1c64ac 100644
--- a/Tools/AP_Bootloader/bl_protocol.cpp
+++ b/Tools/AP_Bootloader/bl_protocol.cpp
@@ -41,6 +41,7 @@
 
 #include <AP_HAL/AP_HAL.h>
 #include <AP_Math/AP_Math.h>
+#include <AP_Math/crc.h>
 #include "ch.h"
 #include "hal.h"
 #include "hwdef.h"
@@ -319,38 +320,6 @@ cout_word(uint32_t val)
     cout((uint8_t *)&val, 4);
 }
 
-static uint32_t
-crc32(const uint8_t *src, unsigned len, unsigned state)
-{
-    static uint32_t crctab[256];
-
-    /* check whether we have generated the CRC table yet */
-    /* this is much smaller than a static table */
-    if (crctab[1] == 0) {
-        for (unsigned i = 0; i < 256; i++) {
-            uint32_t c = i;
-
-            for (unsigned j = 0; j < 8; j++) {
-                if (c & 1) {
-                    c = 0xedb88320U ^ (c >> 1);
-
-                } else {
-                    c = c >> 1;
-                }
-            }
-
-            crctab[i] = c;
-        }
-    }
-
-    for (unsigned i = 0; i < len; i++) {
-        state = crctab[(state ^ src[i]) & 0xff] ^ (state >> 8);
-    }
-
-    return state;
-}
-
-
 /*
   we use a write buffer for flashing, both for efficiency and to
   ensure that we only ever do 32 byte aligned writes on STM32H7. If
@@ -732,7 +701,7 @@ bootloader(unsigned timeout)
                 } else {
                     bytes = flash_func_read_word(p);
                 }
-                sum = crc32((uint8_t *)&bytes, sizeof(bytes), sum);
+                sum = crc32_small(sum, (uint8_t *)&bytes, sizeof(bytes));
             }
 
             cout_word(sum);