diff --git a/MaterialLib/MPL/Medium.cpp b/MaterialLib/MPL/Medium.cpp
index 094bb66d2b473db2941a94a8fa65e2b51e04fcb3..0d9abb04a46604a1e3dbb021b44b53e9c9225ca8 100644
--- a/MaterialLib/MPL/Medium.cpp
+++ b/MaterialLib/MPL/Medium.cpp
@@ -44,6 +44,12 @@ Phase const& Medium::phase(std::string const& name) const
 
 Property const& Medium::property(PropertyType const& p) const
 {
+    Property const* const property = properties_[p].get();
+    if (property == nullptr)
+    {
+        OGS_FATAL("Trying to access undefined property '{:s}' of {:s}",
+                  property_enum_to_string[p], description());
+    }
     return *properties_[p];
 }