diff --git a/compat/lwipr_compat.c b/compat/lwipr_compat.c
index 834b3f071..a334454fb 100644
--- a/compat/lwipr_compat.c
+++ b/compat/lwipr_compat.c
@@ -217,6 +217,9 @@ int ax_get_file(const char *filename, uint8_t **buf) {
     return 0;
 }
 
+void ax_wdt_feed() {
+}
+
 /*
  * Utility functions
  */
diff --git a/crypto/bigint.c b/crypto/bigint.c
index e9ca04cb9..3d44def09 100644
--- a/crypto/bigint.c
+++ b/crypto/bigint.c
@@ -1218,6 +1218,7 @@ bigint *bi_mont(BI_CTX *ctx, bigint *bixy)
 
     check(bixy);
 
+    ax_wdt_feed();
     if (ctx->use_classical)     /* just use classical instead */
     {
         return bi_mod(ctx, bixy);
@@ -1274,6 +1275,7 @@ bigint *bi_barrett(BI_CTX *ctx, bigint *bi)
     check(bi);
     check(bim);
 
+    ax_wdt_feed();
     /* use Classical method instead  - Barrett cannot help here */
     if (bi->size > k*2)
     {
diff --git a/ssl/os_port.h b/ssl/os_port.h
index 73a0e917b..c11ec3bd3 100644
--- a/ssl/os_port.h
+++ b/ssl/os_port.h
@@ -81,6 +81,8 @@ extern "C" {
 #define hmac_sha1 ax_hmac_sha1
 #define hmac_md5 ax_hmac_md5
 
+void ax_wdt_feed();
+
 #elif defined(WIN32)
 
 /* Windows CE stuff */