@@ -131,6 +131,11 @@ jobs:
           echo "$HOME/NJOY2016/build" >> $GITHUB_PATH
           $GITHUB_WORKSPACE/tools/ci/gha-install.sh
 
+      - name: display-config
+        shell: bash
+        run: |
+          openmc -v
+
       - name: cache-xs
         uses: actions/cache@v4
         with:
 
@@ -510,6 +510,14 @@ endif()
 if(OPENMC_USE_DAGMC)
   target_compile_definitions(libopenmc PRIVATE DAGMC)
   target_link_libraries(libopenmc dagmc-shared)
+
+  if(OPENMC_USE_UWUW)
+    target_compile_definitions(libopenmc PRIVATE OPENMC_UWUW)
+    target_link_libraries(libopenmc uwuw-shared)
+  endif()
+elseif(OPENMC_USE_UWUW)
+  set(OPENMC_USE_UWUW OFF)
+  message(FATAL_ERROR "DAGMC must be enabled when UWUW is enabled.")
 endif()
 
 if(OPENMC_USE_LIBMESH)
@@ -546,11 +554,6 @@ if(OPENMC_USE_NCRYSTAL)
   target_link_libraries(libopenmc NCrystal::NCrystal)
 endif()
 
-if (OPENMC_USE_UWUW)
-  target_compile_definitions(libopenmc PRIVATE UWUW)
-  target_link_libraries(libopenmc uwuw-shared)
-endif()
-
 #===============================================================================
 # Log build info that this executable can report later
 #===============================================================================
 
@@ -39,6 +39,6 @@ if(@OPENMC_USE_MCPL@)
   find_package(MCPL REQUIRED)
 endif()
 
-if(@OPENMC_USE_UWUW@)
-  find_package(UWUW REQUIRED)
-endif()
+if(@OPENMC_USE_UWUW@ AND NOT ${DAGMC_BUILD_UWUW})
+  message(FATAL_ERROR "UWUW is enabled in OpenMC but the DAGMC installation discovered was not configured with UWUW.")
+endif()
@@ -11,7 +11,7 @@
 #include "openmc/settings.h"
 #include "openmc/string_utils.h"
 
-#ifdef UWUW
+#ifdef OPENMC_UWUW
 #include "uwuw.hpp"
 #endif
 #include <fmt/core.h>
@@ -29,7 +29,7 @@ const bool DAGMC_ENABLED = true;
 const bool DAGMC_ENABLED = false;
 #endif
 
-#ifdef UWUW
+#ifdef OPENMC_UWUW
 const bool UWUW_ENABLED = true;
 #else
 const bool UWUW_ENABLED = false;
@@ -112,6 +112,11 @@ void DAGUniverse::initialize()
 {
   geom_type() = GeometryType::DAG;
 
+#ifdef OPENMC_UWUW
+  // read uwuw materials from the .h5m file if present
+  read_uwuw_materials();
+#endif
+
   init_dagmc();
 
   init_metadata();
@@ -431,16 +436,16 @@ void DAGUniverse::to_hdf5(hid_t universes_group) const
 
 bool DAGUniverse::uses_uwuw() const
 {
-#ifdef UWUW
+#ifdef OPENMC_UWUW
   return uwuw_ && !uwuw_->material_library.empty();
 #else
   return false;
-#endif // UWUW
+#endif // OPENMC_UWUW
 }
 
 std::string DAGUniverse::get_uwuw_materials_xml() const
 {
-#ifdef UWUW
+#ifdef OPENMC_UWUW
   if (!uses_uwuw()) {
     throw std::runtime_error("This DAGMC Universe does not use UWUW materials");
   }
@@ -460,12 +465,12 @@ std::string DAGUniverse::get_uwuw_materials_xml() const
   return ss.str();
 #else
   fatal_error("DAGMC was not configured with UWUW.");
-#endif // UWUW
+#endif // OPENMC_UWUW
 }
 
 void DAGUniverse::write_uwuw_materials_xml(const std::string& outfile) const
 {
-#ifdef UWUW
+#ifdef OPENMC_UWUW
   if (!uses_uwuw()) {
     throw std::runtime_error(
       "This DAGMC universe does not use UWUW materials.");
@@ -478,7 +483,7 @@ void DAGUniverse::write_uwuw_materials_xml(const std::string& outfile) const
   mats_xml.close();
 #else
   fatal_error("DAGMC was not configured with UWUW.");
-#endif
+#endif // OPENMC_UWUW
 }
 
 void DAGUniverse::legacy_assign_material(
@@ -540,7 +545,7 @@ void DAGUniverse::legacy_assign_material(
 
 void DAGUniverse::read_uwuw_materials()
 {
-#ifdef UWUW
+#ifdef OPENMC_UWUW
   // If no filename was provided, don't read UWUW materials
   if (filename_ == "")
     return;
@@ -580,16 +585,13 @@ void DAGUniverse::read_uwuw_materials()
   }
 #else
   fatal_error("DAGMC was not configured with UWUW.");
-#endif
+#endif // OPENMC_UWUW
 }
 
 void DAGUniverse::uwuw_assign_material(
   moab::EntityHandle vol_handle, std::unique_ptr<DAGCell>& c) const
 {
-#ifdef UWUW
-  // read materials from uwuw material file
-  read_uwuw_materials();
-
+#ifdef OPENMC_UWUW
   // lookup material in uwuw if present
   std::string uwuw_mat = dmd_ptr->volume_material_property_data_eh[vol_handle];
   if (uwuw_->material_library.count(uwuw_mat) != 0) {
@@ -601,11 +603,11 @@ void DAGUniverse::uwuw_assign_material(
   } else {
     fatal_error(fmt::format("Material with value '{}' not found in the "
                             "UWUW material library",
-      mat_str));
+      uwuw_mat));
   }
 #else
   fatal_error("DAGMC was not configured with UWUW.");
-#endif
+#endif // OPENMC_UWUW
 }
 //==============================================================================
 // DAGMC Cell implementation
 
@@ -347,7 +347,7 @@ void print_build_info()
 #ifdef COVERAGEBUILD
   coverage = y;
 #endif
-#ifdef UWUW
+#ifdef OPENMC_UWUW
   uwuw = y;
 #endif