diff --git a/mongoose.c b/mongoose.c
index 16a6ee38..e3226480 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -9208,7 +9208,9 @@ static void sub(fe out, const fe a, const fe b) {
   propagate(out, (limb_t) (1 + carry));
 }
 
-static void mul(fe out, const fe a, const fe b, unsigned nb) {
+// `b` can contain less than 8 limbs, thus we use `limb_t *` instead of `fe`
+// to avoid build warnings
+static void mul(fe out, const fe a, const limb_t *b, unsigned nb) {
   limb_t accum[2 * NLIMBS] = {0};
   unsigned i, j;
 
diff --git a/src/tls_builtin.c b/src/tls_builtin.c
index 031679b7..97da2137 100644
--- a/src/tls_builtin.c
+++ b/src/tls_builtin.c
@@ -116,7 +116,9 @@ static void sub(fe out, const fe a, const fe b) {
   propagate(out, (limb_t) (1 + carry));
 }
 
-static void mul(fe out, const fe a, const fe b, unsigned nb) {
+// `b` can contain less than 8 limbs, thus we use `limb_t *` instead of `fe`
+// to avoid build warnings
+static void mul(fe out, const fe a, const limb_t *b, unsigned nb) {
   limb_t accum[2 * NLIMBS] = {0};
   unsigned i, j;