diff --git a/library/x509write_crt.c b/library/x509write_crt.c
index c970b6ff0..8e4bc35b4 100644
--- a/library/x509write_crt.c
+++ b/library/x509write_crt.c
@@ -395,16 +395,21 @@ int mbedtls_x509write_crt_der( mbedtls_x509write_cert *ctx, unsigned char *buf,
     /*
      *  Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }
      */
-    sub_len = 0;
-    MBEDTLS_ASN1_CHK_ADD( sub_len, mbedtls_asn1_write_int( &c, tmp_buf, ctx->version ) );
-    len += sub_len;
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, sub_len ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC |
-                                                    MBEDTLS_ASN1_CONSTRUCTED | 0 ) );
+
+    /* Can be omitted for v1 */
+    if( ctx->version > 0 )
+    {
+        sub_len = 0;
+        MBEDTLS_ASN1_CHK_ADD( sub_len, mbedtls_asn1_write_int( &c, tmp_buf, ctx->version ) );
+        len += sub_len;
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, sub_len ) );
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC |
+                                                           MBEDTLS_ASN1_CONSTRUCTED | 0 ) );
+    }
 
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
-                                                    MBEDTLS_ASN1_SEQUENCE ) );
+                                                       MBEDTLS_ASN1_SEQUENCE ) );
 
     /*
      * Make signature
diff --git a/tests/data_files/server1.v1.crt b/tests/data_files/server1.v1.crt
index 0a4b2a5cc..b13be4351 100644
--- a/tests/data_files/server1.v1.crt
+++ b/tests/data_files/server1.v1.crt
@@ -1,18 +1,18 @@
 -----BEGIN CERTIFICATE-----
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+IKqsWradEnFG/1ov78a2RB+2+iIPE4iCDtmKUkgPjQ==
 -----END CERTIFICATE-----