diff --git a/src/x509.c b/src/x509.c
index d9e948fe943..096cead95db 100644
--- a/src/x509.c
+++ b/src/x509.c
@@ -8640,6 +8640,11 @@ static int x509AddCertDir(WOLFSSL_BY_DIR *ctx, const char *argc, long argl)
             pathLen = 0;
             XMEMSET(buf, 0, MAX_FILENAME_SZ);
         }
+        if (pathLen >= MAX_FILENAME_SZ) {
+            WOLFSSL_MSG("Could not write full dir name not enough space");
+                WC_FREE_VAR_EX(buf, 0, DYNAMIC_TYPE_OPENSSL);
+            return 0;
+        }
         buf[pathLen++] = *c;
 
     } while(*c++ != '\0');
diff --git a/tests/api/test_ossl_x509_lu.c b/tests/api/test_ossl_x509_lu.c
index 07213e61369..d89fdd9b12c 100644
--- a/tests/api/test_ossl_x509_lu.c
+++ b/tests/api/test_ossl_x509_lu.c
@@ -294,6 +294,63 @@ int test_wolfSSL_X509_LOOKUP_ctrl_hash_dir(void)
     return EXPECT_RESULT();
 }
 
+/* Check that a path element longer than the internal MAX_FILENAME_SZ buffer is
+ * rejected instead of overflowing it. */
+int test_wolfSSL_X509_LOOKUP_ctrl_dir_len(void)
+{
+    EXPECT_DECLS;
+#if defined(OPENSSL_ALL) && !defined(NO_FILESYSTEM) && !defined(NO_WOLFSSL_DIR)
+    X509_STORE* str = NULL;
+    X509_LOOKUP* lookup = NULL;
+    char* longPath = NULL;
+    char maxPath[MAX_FILENAME_SZ + 1];
+
+    /* one element that does not fit in the buffer - must fail */
+    ExpectNotNull(longPath = (char*)XMALLOC(MAX_FILENAME_SZ + 4, NULL,
+        DYNAMIC_TYPE_TMP_BUFFER));
+    if (longPath != NULL) {
+        XMEMSET(longPath, 'a', MAX_FILENAME_SZ + 3);
+        longPath[MAX_FILENAME_SZ + 3] = '\0';
+    }
+
+    ExpectNotNull((str = wolfSSL_X509_STORE_new()));
+    ExpectNotNull(lookup = X509_STORE_add_lookup(str, X509_LOOKUP_file()));
+    ExpectIntEQ(X509_LOOKUP_ctrl(lookup, X509_L_ADD_DIR, longPath,
+        SSL_FILETYPE_PEM, NULL), 0);
+
+    X509_STORE_free(str);
+    str = NULL;
+
+    /* oversized element preceded by a valid one - still fails */
+    ExpectNotNull((str = wolfSSL_X509_STORE_new()));
+    ExpectNotNull(lookup = X509_STORE_add_lookup(str, X509_LOOKUP_file()));
+    if (longPath != NULL) {
+        longPath[0] = '.';
+        longPath[1] = SEPARATOR_CHAR;
+    }
+    ExpectIntEQ(X509_LOOKUP_ctrl(lookup, X509_L_ADD_DIR, longPath,
+        SSL_FILETYPE_PEM, NULL), 0);
+
+    X509_STORE_free(str);
+    str = NULL;
+
+    XFREE(longPath, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    longPath = NULL;
+
+    /* an element that exactly fills the buffer is still accepted */
+    XMEMSET(maxPath, 'a', MAX_FILENAME_SZ);
+    maxPath[MAX_FILENAME_SZ] = '\0';
+
+    ExpectNotNull((str = wolfSSL_X509_STORE_new()));
+    ExpectNotNull(lookup = X509_STORE_add_lookup(str, X509_LOOKUP_file()));
+    ExpectIntEQ(X509_LOOKUP_ctrl(lookup, X509_L_ADD_DIR, maxPath,
+        SSL_FILETYPE_PEM, NULL), 1);
+
+    X509_STORE_free(str);
+#endif
+    return EXPECT_RESULT();
+}
+
 int test_wolfSSL_X509_load_crl_file(void)
 {
     EXPECT_DECLS;
diff --git a/tests/api/test_ossl_x509_lu.h b/tests/api/test_ossl_x509_lu.h
index 72a7991b1e8..28fffcc3325 100644
--- a/tests/api/test_ossl_x509_lu.h
+++ b/tests/api/test_ossl_x509_lu.h
@@ -27,6 +27,7 @@
 int test_wolfSSL_X509_LOOKUP_load_file(void);
 int test_wolfSSL_X509_LOOKUP_ctrl_file(void);
 int test_wolfSSL_X509_LOOKUP_ctrl_hash_dir(void);
+int test_wolfSSL_X509_LOOKUP_ctrl_dir_len(void);
 int test_wolfSSL_X509_load_crl_file(void);
 int test_X509_LOOKUP_add_dir(void);
 
@@ -34,6 +35,7 @@ int test_X509_LOOKUP_add_dir(void);
     TEST_DECL_GROUP("ossl_x509_lu", test_wolfSSL_X509_LOOKUP_load_file),       \
     TEST_DECL_GROUP("ossl_x509_lu", test_wolfSSL_X509_LOOKUP_ctrl_file),       \
     TEST_DECL_GROUP("ossl_x509_lu", test_wolfSSL_X509_LOOKUP_ctrl_hash_dir),   \
+    TEST_DECL_GROUP("ossl_x509_lu", test_wolfSSL_X509_LOOKUP_ctrl_dir_len),    \
     TEST_DECL_GROUP("ossl_x509_lu", test_wolfSSL_X509_load_crl_file),          \
     TEST_DECL_GROUP("ossl_x509_lu", test_X509_LOOKUP_add_dir)