diff --git a/library/pkcs7.c b/library/pkcs7.c
index 9ef7608..fbe959e 100644
--- a/library/pkcs7.c
+++ b/library/pkcs7.c
@@ -57,9 +57,9 @@
     ret = mbedtls_asn1_get_tag(p, end, len, MBEDTLS_ASN1_CONSTRUCTED
                                | MBEDTLS_ASN1_CONTEXT_SPECIFIC);
     if (ret != 0) {
-        ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_FORMAT, ret);
+        ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_CONTENT_INFO, ret);
     } else if ((size_t) (end - *p) != *len) {
-        ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_FORMAT,
+        ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_CONTENT_INFO,
                                 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
     }
 
@@ -187,13 +187,13 @@
     size_t len2 = 0;
     unsigned char *end_set, *end_cert, *start;
 
-    if ((ret = mbedtls_asn1_get_tag(p, end, &len1, MBEDTLS_ASN1_CONSTRUCTED
-                                    | MBEDTLS_ASN1_CONTEXT_SPECIFIC)) != 0) {
-        if (ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) {
-            return 0;
-        } else {
-            return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_FORMAT, ret);
-        }
+    ret = mbedtls_asn1_get_tag(p, end, &len1, MBEDTLS_ASN1_CONSTRUCTED
+                               | MBEDTLS_ASN1_CONTEXT_SPECIFIC);
+    if (ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) {
+        return 0;
+    }
+    if (ret != 0) {
+        return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS7_INVALID_FORMAT, ret);
     }
     start = *p;
     end_set = *p + len1;
@@ -716,11 +716,15 @@
 
     return ret;
 }
+
 int mbedtls_pkcs7_signed_data_verify(mbedtls_pkcs7 *pkcs7,
                                      const mbedtls_x509_crt *cert,
                                      const unsigned char *data,
                                      size_t datalen)
 {
+    if (data == NULL) {
+        return MBEDTLS_ERR_PKCS7_BAD_INPUT_DATA;
+    }
     return mbedtls_pkcs7_data_or_hash_verify(pkcs7, cert, data, datalen, 0);
 }
 
@@ -729,6 +733,9 @@
                                      const unsigned char *hash,
                                      size_t hashlen)
 {
+    if (hash == NULL) {
+        return MBEDTLS_ERR_PKCS7_BAD_INPUT_DATA;
+    }
     return mbedtls_pkcs7_data_or_hash_verify(pkcs7, cert, hash, hashlen, 1);
 }