diff --git a/expat/xmlparse/Makefile.in b/expat/xmlparse/Makefile.in
index caf407f6b72d..976e4bfddb2d 100644
--- a/expat/xmlparse/Makefile.in
+++ b/expat/xmlparse/Makefile.in
@@ -28,6 +28,7 @@ ifdef MOZ_STRIP_NOT_EXPORTED
 DEFINES += -DXMLPARSEAPI="__attribute__ ((dllexport))"
 endif
 
+DEFINES += -DXML_DTD
 
 CSRCS = \
 	hashtable.c \
diff --git a/expat/xmlparse/makefile.win b/expat/xmlparse/makefile.win
index 7d3fdc1c528f..b6468ffbd9f9 100644
--- a/expat/xmlparse/makefile.win
+++ b/expat/xmlparse/makefile.win
@@ -18,7 +18,7 @@
 #
 
 DEPTH= ..\..
-
+DEFINES=-DXML_DTD
 MODULE = expat
 EXPORTS = xmlparse.h
 
diff --git a/expat/xmltok/Makefile.in b/expat/xmltok/Makefile.in
index 38a9ce1a4966..34ada66edc0a 100644
--- a/expat/xmltok/Makefile.in
+++ b/expat/xmltok/Makefile.in
@@ -28,6 +28,8 @@ ifdef MOZ_STRIP_NOT_EXPORTED
 DEFINES += -DXMLTOKAPI="__attribute__ ((dllexport))"
 endif
 
+DEFINES += -DXML_DTD
+
 CSRCS = \
 	xmltok.c \
 	xmlrole.c \
diff --git a/expat/xmltok/makefile.win b/expat/xmltok/makefile.win
index 6410b5cf78e0..53842ba8e8b5 100644
--- a/expat/xmltok/makefile.win
+++ b/expat/xmltok/makefile.win
@@ -17,6 +17,7 @@
 
 #
 
+DEFINES=-DXML_DTD
 DEPTH= ..\..
 
 OBJS=                                   \
diff --git a/parser/expat/lib/Makefile.in b/parser/expat/lib/Makefile.in
index caf407f6b72d..976e4bfddb2d 100644
--- a/parser/expat/lib/Makefile.in
+++ b/parser/expat/lib/Makefile.in
@@ -28,6 +28,7 @@ ifdef MOZ_STRIP_NOT_EXPORTED
 DEFINES += -DXMLPARSEAPI="__attribute__ ((dllexport))"
 endif
 
+DEFINES += -DXML_DTD
 
 CSRCS = \
 	hashtable.c \