diff --git a/src/initialize.cpp b/src/initialize.cpp
index c6d8250c1..d30581e06 100644
--- a/src/initialize.cpp
+++ b/src/initialize.cpp
@@ -68,7 +68,7 @@ int openmc_init(int argc, char* argv[], const void* intracomm)
 #endif
 
 // initialize libMesh if it hasn't been initialized already
-// by a call external to OpenMC
+// (if initialized externally, the LMI object needs to be provided also)
 if (!settings::LMI && !libMesh::initialized())
 {
 #ifdef OPENMC_MPI
@@ -81,6 +81,10 @@ if (!settings::LMI && !libMesh::initialized())
   settings::LMI = std::make_unique<libMesh::LibMeshInit>(argc, argv, 0, n_threads);
 #endif
 }
+
+if (!settings::LMI) {
+  fatal_error("libMesh::LibMeshInit object isn't set.");
+}
 #endif
 
   // Start total and initialization timer