diff --git a/doc/doxygen/Doxyfile b/doc/doxygen/Doxyfile
index 4ed4ed877..493f3377e 100644
--- a/doc/doxygen/Doxyfile
+++ b/doc/doxygen/Doxyfile
@@ -1299,6 +1299,7 @@ PREDEFINED             = WITH_HTML_LOGS \
                          HAS_SUNDIALS \
                          SUNDIALS_VERSION=25 \
                          THREAD_SAFE_CANTERA \
+                         DEBUG_MODE \
                          HAVE_CONFIG_H \
                          DEPRECATED(x)=x
 
diff --git a/include/cantera/thermo/PDSS_HKFT.h b/include/cantera/thermo/PDSS_HKFT.h
index b9a1c2d07..b0a13b171 100644
--- a/include/cantera/thermo/PDSS_HKFT.h
+++ b/include/cantera/thermo/PDSS_HKFT.h
@@ -109,6 +109,7 @@ public:
      *  Note this is just an extra routine to check the arithmetic
      *
      * @return returns the species standard state enthalpy in  J kmol-1
+     * @deprecated
      */
     doublereal enthalpy_mole2() const;
 #endif
@@ -257,6 +258,7 @@ private:
     //! between the reference state at Tr, Pr and T,P
     /*!
      *  This is an extra routine that was added to check the arithmetic
+     *  @deprecated
      */
     doublereal deltaH() const;
 #endif