diff --git a/libraries/AP_Networking/AP_Networking.cpp b/libraries/AP_Networking/AP_Networking.cpp
index 87ca70bd94ad7..87b5147b75f24 100644
--- a/libraries/AP_Networking/AP_Networking.cpp
+++ b/libraries/AP_Networking/AP_Networking.cpp
@@ -293,7 +293,15 @@ bool AP_Networking::sendfile(SocketAPM *sock, int fd)
 {
     WITH_SEMAPHORE(sem);
     if (sendfile_buf == nullptr) {
-        sendfile_buf = (uint8_t *)malloc(AP_NETWORKING_SENDFILE_BUFSIZE);
+        uint32_t bufsize = AP_NETWORKING_SENDFILE_BUFSIZE;
+        do {
+            sendfile_buf = (uint8_t *)hal.util->malloc_type(bufsize, AP_HAL::Util::MEM_FILESYSTEM);
+            if (sendfile_buf != nullptr) {
+                sendfile_bufsize = bufsize;
+                break;
+            }
+            bufsize /= 2;
+        } while (bufsize >= 4096);
         if (sendfile_buf == nullptr) {
             return false;
         }
@@ -344,7 +352,7 @@ void AP_Networking::sendfile_check(void)
             if (!s.sock->pollout(0)) {
                 continue;
             }
-            const auto nread = AP::FS().read(s.fd, sendfile_buf, AP_NETWORKING_SENDFILE_BUFSIZE);
+            const auto nread = AP::FS().read(s.fd, sendfile_buf, sendfile_bufsize);
             if (nread <= 0) {
                 s.close();
                 continue;
diff --git a/libraries/AP_Networking/AP_Networking.h b/libraries/AP_Networking/AP_Networking.h
index 3b18072593b70..63936f025b2c5 100644
--- a/libraries/AP_Networking/AP_Networking.h
+++ b/libraries/AP_Networking/AP_Networking.h
@@ -278,6 +278,7 @@ class AP_Networking
     } sendfiles[AP_NETWORKING_NUM_SENDFILES];
 
     uint8_t *sendfile_buf;
+    uint32_t sendfile_bufsize;
     void sendfile_check(void);
     bool sendfile_thread_started;
 
diff --git a/libraries/AP_Networking/AP_Networking_Config.h b/libraries/AP_Networking/AP_Networking_Config.h
index b9fdbd6fd3fb2..2fbf9d70b15c5 100644
--- a/libraries/AP_Networking/AP_Networking_Config.h
+++ b/libraries/AP_Networking/AP_Networking_Config.h
@@ -117,5 +117,5 @@
 #endif
 
 #ifndef AP_NETWORKING_SENDFILE_BUFSIZE
-#define AP_NETWORKING_SENDFILE_BUFSIZE 10000
+#define AP_NETWORKING_SENDFILE_BUFSIZE (64*512)
 #endif