diff --git a/src/Makefile.am b/src/Makefile.am
index 066f4154925333c6e41425a2f67cf1fda238404e..c90e70ef3bf888a1bd8b175a5df4b87f098d4d77 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -18,7 +18,7 @@
 # $Id$
 #
 
-DEFS = -DXERCES_BUILDING_LIBRARY
+DEFS += -DXERCES_BUILDING_LIBRARY
 SUBDIRS = 
 
 #
diff --git a/src/Makefile.in b/src/Makefile.in
index a0aa15616dc67c2eb86b9e2bdc03e8bf1eeb1d99..8debf39ea8017ac86a21f1119058674a3a4314c2 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -915,7 +915,7 @@ CXXCPP = @CXXCPP@
 CXXDEPMODE = @CXXDEPMODE@
 CXXFLAGS = @CXXFLAGS@
 CYGPATH_W = @CYGPATH_W@
-DEFS = -DXERCES_BUILDING_LIBRARY
+DEFS = @DEFS@ -DXERCES_BUILDING_LIBRARY
 DEPDIR = @DEPDIR@
 DLLTOOL = @DLLTOOL@
 ECHO = @ECHO@