diff --git a/crypto/bn/convert.c b/crypto/bn/convert.c
index 542f523f..9125bf84 100644
--- a/crypto/bn/convert.c
+++ b/crypto/bn/convert.c
@@ -577,12 +577,14 @@ BIGNUM *BN_mpi2bn(const uint8_t *in, size_t len, BIGNUM *out) {
     return NULL;
   }
 
+  int out_is_alloced = 0;
   if (out == NULL) {
     out = BN_new();
-  }
-  if (out == NULL) {
-    OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
-    return NULL;
+    if (out == NULL) {
+      OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
+      return NULL;
+    }
+    out_is_alloced = 1;
   }
 
   if (in_len == 0) {
@@ -592,6 +594,9 @@ BIGNUM *BN_mpi2bn(const uint8_t *in, size_t len, BIGNUM *out) {
 
   in += 4;
   if (BN_bin2bn(in, in_len, out) == NULL) {
+    if (out_is_alloced) {
+      BN_free(out);
+    }
     return NULL;
   }
   out->neg = ((*in) & 0x80) != 0;