diff --git a/src/x509.c b/src/x509.c
index 8fc94f5f1..a34f72df7 100644
--- a/src/x509.c
+++ b/src/x509.c
@@ -3448,25 +3448,25 @@ int wolfSSL_X509_pubkey_digest(const WOLFSSL_X509 *x509,
     const char* wolfSSL_X509_get_default_cert_file_env(void)
     {
         WOLFSSL_STUB("X509_get_default_cert_file_env");
-        return NULL;
+        return "";
     }
 
     const char* wolfSSL_X509_get_default_cert_file(void)
     {
         WOLFSSL_STUB("X509_get_default_cert_file");
-        return NULL;
+        return "";
     }
 
     const char* wolfSSL_X509_get_default_cert_dir_env(void)
     {
         WOLFSSL_STUB("X509_get_default_cert_dir_env");
-        return NULL;
+        return "";
     }
 
     const char* wolfSSL_X509_get_default_cert_dir(void)
     {
         WOLFSSL_STUB("X509_get_default_cert_dir");
-        return NULL;
+        return "";
     }
     #endif
 
diff --git a/tests/api/test_ossl_x509.c b/tests/api/test_ossl_x509.c
index b198da11d..a28728800 100644
--- a/tests/api/test_ossl_x509.c
+++ b/tests/api/test_ossl_x509.c
@@ -528,10 +528,10 @@ int test_wolfSSL_X509(void)
     ExpectIntEQ(X509_verify_cert(ctx), SSL_SUCCESS);
 
 #ifndef NO_WOLFSSL_STUB
-    ExpectNull(X509_get_default_cert_file_env());
-    ExpectNull(X509_get_default_cert_file());
-    ExpectNull(X509_get_default_cert_dir_env());
-    ExpectNull(X509_get_default_cert_dir());
+    ExpectStrEQ(X509_get_default_cert_file_env(), "");
+    ExpectStrEQ(X509_get_default_cert_file(), "");
+    ExpectStrEQ(X509_get_default_cert_dir_env(), "");
+    ExpectStrEQ(X509_get_default_cert_dir(), "");
 #endif
 
     ExpectNull(wolfSSL_X509_get_der(NULL, NULL));