diff --git a/include/amici/defines.h b/include/amici/defines.h
index bd97d9a0b2..6ccba89923 100644
--- a/include/amici/defines.h
+++ b/include/amici/defines.h
@@ -71,6 +71,7 @@ constexpr int AMICI_CONV_FAILURE=             -4;
 constexpr int AMICI_LSETUP_FAIL=              -6;
 constexpr int AMICI_RHSFUNC_FAIL=             -8;
 constexpr int AMICI_FIRST_RHSFUNC_ERR=        -9;
+constexpr int AMICI_CONSTR_FAIL=             -15;
 constexpr int AMICI_ILL_INPUT=               -22;
 constexpr int AMICI_ERROR=                   -99;
 constexpr int AMICI_NO_STEADY_STATE=         -81;
diff --git a/src/amici.cpp b/src/amici.cpp
index 2f60a8e12a..c74c88e3a5 100644
--- a/src/amici.cpp
+++ b/src/amici.cpp
@@ -59,6 +59,7 @@ std::map<int, std::string> simulation_status_to_str_map = {
     {AMICI_ERR_FAILURE, "AMICI_ERR_FAILURE"},
     {AMICI_CONV_FAILURE, "AMICI_CONV_FAILURE"},
     {AMICI_FIRST_RHSFUNC_ERR, "AMICI_FIRST_RHSFUNC_ERR"},
+    {AMICI_CONSTR_FAIL, "AMICI_CONSTR_FAIL"},
     {AMICI_RHSFUNC_FAIL, "AMICI_RHSFUNC_FAIL"},
     {AMICI_ILL_INPUT, "AMICI_ILL_INPUT"},
     {AMICI_ERROR, "AMICI_ERROR"},