diff --git a/ChangeLog b/ChangeLog
index 008a16f..316009d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,9 @@
 Bugfix
 
    * Fix braces in mbedtls_memory_buffer_alloc_status(). Found by sbranden, #552.
+   * Added the macro MBEDTLS_X509_MAX_FILE_PATH_LEN that enables the user to
+     configure the maximum length of a file path that can be buffered when
+     calling mbedtls_x509_crt_parse_path().
 
 = mbed TLS 2.1.12 branch released 2018-04-30
 
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 0444eb1..9689643 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -2492,6 +2492,7 @@
 
 /* X509 options */
 //#define MBEDTLS_X509_MAX_INTERMEDIATE_CA   8   /**< Maximum number of intermediate CAs in a verification chain. */
+//#define MBEDTLS_X509_MAX_FILE_PATH_LEN     512 /**< Maximum length of a path/filename string in bytes including the null terminator character ('\0'). */
 
 /**
  * Allow SHA-1 in the default TLS configuration for certificate signing.
diff --git a/include/mbedtls/x509_crt.h b/include/mbedtls/x509_crt.h
index f82f91f..3548b9a 100644
--- a/include/mbedtls/x509_crt.h
+++ b/include/mbedtls/x509_crt.h
@@ -120,6 +120,10 @@
 #define MBEDTLS_X509_RFC5280_MAX_SERIAL_LEN 32
 #define MBEDTLS_X509_RFC5280_UTC_TIME_LEN   15
 
+#if !defined( MBEDTLS_X509_MAX_FILE_PATH_LEN )
+#define MBEDTLS_X509_MAX_FILE_PATH_LEN 512
+#endif
+
 /**
  * Container for writing a certificate (CRT)
  */
diff --git a/library/x509_crt.c b/library/x509_crt.c
index e797355..f567afc 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -1169,9 +1169,10 @@
     FindClose( hFind );
 #else /* _WIN32 */
     int t_ret;
+    int snp_ret;
     struct stat sb;
     struct dirent *entry;
-    char entry_name[255];
+    char entry_name[MBEDTLS_X509_MAX_FILE_PATH_LEN];
     DIR *dir = opendir( path );
 
     if( dir == NULL )
@@ -1187,11 +1188,16 @@
 
     while( ( entry = readdir( dir ) ) != NULL )
     {
-        mbedtls_snprintf( entry_name, sizeof entry_name, "%s/%s", path, entry->d_name );
+        snp_ret = mbedtls_snprintf( entry_name, sizeof entry_name,
+                                    "%s/%s", path, entry->d_name );
 
-        if( stat( entry_name, &sb ) == -1 )
+        if( snp_ret < 0 || (size_t)snp_ret >= sizeof entry_name )
         {
-            closedir( dir );
+            ret = MBEDTLS_ERR_X509_BUFFER_TOO_SMALL;
+            goto cleanup;
+        }
+        else if( stat( entry_name, &sb ) == -1 )
+        {
             ret = MBEDTLS_ERR_X509_FILE_IO_ERROR;
             goto cleanup;
         }
@@ -1207,9 +1213,10 @@
         else
             ret += t_ret;
     }
-    closedir( dir );
 
 cleanup:
+    closedir( dir );
+
 #if defined(MBEDTLS_THREADING_C)
     if( mbedtls_mutex_unlock( &mbedtls_threading_readdir_mutex ) != 0 )
         ret = MBEDTLS_ERR_THREADING_MUTEX_ERROR;