diff --git a/library/x509_create.c b/library/x509_create.c
index 271d4f1..3074ce4 100644
--- a/library/x509_create.c
+++ b/library/x509_create.c
@@ -218,8 +218,6 @@
                                                  size_t *data_len,
                                                  int *tag)
 {
-    unsigned char *p;
-
     /* Step 1: preliminary length checks. */
     /* Each byte is encoded by exactly two hexadecimal digits. */
     if (len % 2 != 0) {
@@ -256,31 +254,33 @@
     /* Step 3: decode the DER. */
     /* We've checked that der_length >= 1 above. */
     *tag = der[0];
-    p = der + 1;
-    if (mbedtls_asn1_get_len(&p, der + der_length, data_len) != 0) {
-        goto error;
-    }
-    /* Now p points to the first byte of the payload inside der,
-     * and *data_len is the length of the payload. */
+    {
+        unsigned char *p = der + 1;
+        if (mbedtls_asn1_get_len(&p, der + der_length, data_len) != 0) {
+            goto error;
+        }
+        /* Now p points to the first byte of the payload inside der,
+        * and *data_len is the length of the payload. */
 
-    /* Step 4: payload validation */
-    if (*data_len > MBEDTLS_X509_MAX_DN_NAME_SIZE) {
-        goto error;
-    }
-    /* Strings must not contain null bytes. */
-    if (MBEDTLS_ASN1_IS_STRING_TAG(*tag)) {
-        for (size_t i = 0; i < *data_len; i++) {
-            if (p[i] == 0) {
-                goto error;
+        /* Step 4: payload validation */
+        if (*data_len > MBEDTLS_X509_MAX_DN_NAME_SIZE) {
+            goto error;
+        }
+        /* Strings must not contain null bytes. */
+        if (MBEDTLS_ASN1_IS_STRING_TAG(*tag)) {
+            for (size_t i = 0; i < *data_len; i++) {
+                if (p[i] == 0) {
+                    goto error;
+                }
             }
         }
-    }
 
-    /* Step 5: output the payload. */
-    if (*data_len > data_size) {
-        goto error;
+        /* Step 5: output the payload. */
+        if (*data_len > data_size) {
+            goto error;
+        }
+        memcpy(data, p, *data_len);
     }
-    memcpy(data, p, *data_len);
     mbedtls_free(der);
 
     return 0;