diff --git a/configure.ac b/configure.ac
index f4bcd5bb..2e1682c9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -255,8 +255,12 @@ AC_SUBST(ANTIOCH_STAMPED_FILES)
 # step (see install-data-hook)
 # to make it $datadir/antioch_default_files
 # then we define the default files
-ANTIOCH_DEFAULT_FILES_PATH_TMP=$TOP_SEARCH_DIR/share/antioch_default_files/
-AC_DEFINE_UNQUOTED(DEFAULT_FILES_PATH,"$ANTIOCH_DEFAULT_FILES_PATH_TMP",[Path to defaults files])
+# Need to make sure to have the `/` at the end
+ANTIOCH_DEFAULT_FILES_SOURCE_PATH_TMP=$TOP_SEARCH_DIR/share/antioch_default_files/
+ANTIOCH_DEFAULT_FILES_INSTALL_PATH_TMP=$prefix/share/antioch_default_files/
+
+AC_DEFINE_UNQUOTED(DEFAULT_FILES_SOURCE_PATH,"$ANTIOCH_DEFAULT_FILES_SOURCE_PATH_TMP",[Path to defaults files])
+AC_DEFINE_UNQUOTED(DEFAULT_FILES_INSTALL_PATH,"$ANTIOCH_DEFAULT_FILES_INSTALL_PATH_TMP",[Path to defaults files])
 AC_DEFINE(DEFAULT_SPECIES_LIST,"antioch_default_chemical_species.dat",[Default list of species])
 AC_DEFINE(DEFAULT_CHEMICAL_MIXTURE,"antioch_default_chemical_mixture.dat",[Mandatory default informations on species])
 AC_DEFINE(DEFAULT_VIBRATIONAL_DATA,"antioch_default_vibrational_data.dat",[Vibrational default data])
diff --git a/src/utilities/include/antioch/default_filename.h b/src/utilities/include/antioch/default_filename.h
index 7c4e1f1c..907ee82d 100644
--- a/src/utilities/include/antioch/default_filename.h
+++ b/src/utilities/include/antioch/default_filename.h
@@ -38,65 +38,138 @@
 // C++ headers
 #include <string>
 
-// Create shim methods Antioch::ant_exp() for exp(), etcetera.
-
 namespace Antioch
 {
 
-class DefaultFilename {
+  //! Default filenames in the source tree
+  /*! These include the full path to default files in
+   *  in the Antioch *source* tree. If you decide to use
+   *  these in your application, you must *not* delete the
+   *  source tree.
+   */
+class DefaultSourceFilename {
+public:
+  static const std::string& species_list() {
+    static const std::string filename =
+      std::string(ANTIOCH_DEFAULT_FILES_SOURCE_PATH) +
+      std::string(ANTIOCH_DEFAULT_SPECIES_LIST);
+    return filename;
+  }
+
+  static const std::string& chemical_mixture() {
+    static const std::string filename =
+      std::string(ANTIOCH_DEFAULT_FILES_SOURCE_PATH) +
+      std::string(ANTIOCH_DEFAULT_CHEMICAL_MIXTURE);
+    return filename;
+  }
+
+  static const std::string& vibrational_data() {
+    static const std::string filename =
+      std::string(ANTIOCH_DEFAULT_FILES_SOURCE_PATH) +
+      std::string(ANTIOCH_DEFAULT_VIBRATIONAL_DATA);
+    return filename;
+  }
+
+  static const std::string& electronic_data() {
+    static const std::string filename =
+      std::string(ANTIOCH_DEFAULT_FILES_SOURCE_PATH) +
+      std::string(ANTIOCH_DEFAULT_ELECTRONIC_DATA);
+    return filename;
+  }
+
+  static const std::string& thermo_data() {
+    static const std::string filename =
+      std::string(ANTIOCH_DEFAULT_FILES_SOURCE_PATH) +
+      std::string(ANTIOCH_DEFAULT_THERMO_DATA);
+    return filename;
+  }
+
+  static const std::string& sutherland_data() {
+    static const std::string filename =
+      std::string(ANTIOCH_DEFAULT_FILES_SOURCE_PATH) +
+      std::string(ANTIOCH_DEFAULT_SUTHERLAND_DATA);
+    return filename;
+  }
+
+  static const std::string& blottner_data() {
+    static const std::string filename =
+      std::string(ANTIOCH_DEFAULT_FILES_SOURCE_PATH) +
+      std::string(ANTIOCH_DEFAULT_BLOTTNER_DATA);
+    return filename;
+  }
+
+  static const std::string& transport_mixture() {
+    static const std::string filename =
+      std::string(ANTIOCH_DEFAULT_FILES_SOURCE_PATH) +
+      std::string(ANTIOCH_DEFAULT_TRANSPORT_DATA);
+    return filename;
+  }
+};
+
+// Backward Compatibility
+typedef DefaultSourceFilename DefaultFilename;
+
+
+  //! Default filenames in the install tree
+  /*! These include the full path to default files in
+   *  in the Antioch *install* tree. These *must not*
+   *  be used internally in Antioch; these are meant
+   *  *only* for applications.
+   */
+class DefaultInstallFilename {
 public:
   static const std::string& species_list() {
     static const std::string filename =
-      std::string(ANTIOCH_DEFAULT_FILES_PATH) +
+      std::string(ANTIOCH_DEFAULT_FILES_INSTALL_PATH) +
       std::string(ANTIOCH_DEFAULT_SPECIES_LIST);
     return filename;
   }
 
   static const std::string& chemical_mixture() {
     static const std::string filename =
-      std::string(ANTIOCH_DEFAULT_FILES_PATH) +
+      std::string(ANTIOCH_DEFAULT_FILES_INSTALL_PATH) +
       std::string(ANTIOCH_DEFAULT_CHEMICAL_MIXTURE);
     return filename;
   }
 
   static const std::string& vibrational_data() {
     static const std::string filename =
-      std::string(ANTIOCH_DEFAULT_FILES_PATH) +
+      std::string(ANTIOCH_DEFAULT_FILES_INSTALL_PATH) +
       std::string(ANTIOCH_DEFAULT_VIBRATIONAL_DATA);
     return filename;
   }
 
   static const std::string& electronic_data() {
     static const std::string filename =
-      std::string(ANTIOCH_DEFAULT_FILES_PATH) +
+      std::string(ANTIOCH_DEFAULT_FILES_INSTALL_PATH) +
       std::string(ANTIOCH_DEFAULT_ELECTRONIC_DATA);
     return filename;
   }
 
   static const std::string& thermo_data() {
     static const std::string filename =
-      std::string(ANTIOCH_DEFAULT_FILES_PATH) +
+      std::string(ANTIOCH_DEFAULT_FILES_INSTALL_PATH) +
       std::string(ANTIOCH_DEFAULT_THERMO_DATA);
     return filename;
   }
 
   static const std::string& sutherland_data() {
     static const std::string filename =
-      std::string(ANTIOCH_DEFAULT_FILES_PATH) +
+      std::string(ANTIOCH_DEFAULT_FILES_INSTALL_PATH) +
       std::string(ANTIOCH_DEFAULT_SUTHERLAND_DATA);
     return filename;
   }
 
   static const std::string& blottner_data() {
     static const std::string filename =
-      std::string(ANTIOCH_DEFAULT_FILES_PATH) +
+      std::string(ANTIOCH_DEFAULT_FILES_INSTALL_PATH) +
       std::string(ANTIOCH_DEFAULT_BLOTTNER_DATA);
     return filename;
   }
 
   static const std::string& transport_mixture() {
     static const std::string filename =
-      std::string(ANTIOCH_DEFAULT_FILES_PATH) +
+      std::string(ANTIOCH_DEFAULT_FILES_INSTALL_PATH) +
       std::string(ANTIOCH_DEFAULT_TRANSPORT_DATA);
     return filename;
   }