diff --git a/test/sig_utils.py b/test/sig_utils.py
index 50a136e3239..73c52f83a90 100644
--- a/test/sig_utils.py
+++ b/test/sig_utils.py
@@ -124,6 +124,7 @@ def get_cpp_type(stan_type):
     "ordered_free": [1.0],
     "simplex_constrain": [None, scalar_return_type],
     "simplex_free": [simplex],
+    "std_normal_log_qf": [-0.1],
     "student_t_cdf": [0.8, None, 0.4, None],
     "student_t_cdf_log": [0.8, None, 0.4, None],
     "student_t_ccdf_log": [0.8, None, 0.4, None],