diff --git a/test_regress/t/t_vpi_var.cpp b/test_regress/t/t_vpi_var.cpp
index 91ba19008..9fdd7dc1b 100644
--- a/test_regress/t/t_vpi_var.cpp
+++ b/test_regress/t/t_vpi_var.cpp
@@ -84,7 +84,7 @@ unsigned int callback_count_strs_max = 500;
 #define CHECK_RESULT_CSTR(got, exp) \
     if (strcmp((got), (exp))) { \
         printf("%%Error: %s:%d: GOT = '%s'   EXP = '%s'\n", FILENM, __LINE__, \
-               (got) ? (got) : "<null>", (exp) ? (exp) : "<null>"); \
+               ((got) != NULL) ? (got) : "<null>", ((exp) != NULL) ? (exp) : "<null>"); \
         return __LINE__; \
     }