diff --git a/content/xslt/src/base/Makefile.in b/content/xslt/src/base/Makefile.in
index 73621e1d8281..256ec154f1b3 100644
--- a/content/xslt/src/base/Makefile.in
+++ b/content/xslt/src/base/Makefile.in
@@ -12,6 +12,7 @@ include $(DEPTH)/config/autoconf.mk
 MODULE = transformiix
 LIBRARY_NAME = txbase_s
 LIBXUL_LIBRARY = 1
+FAIL_ON_WARNINGS = 1
 
 CPPSRCS	= txDouble.cpp \
 	txList.cpp \
diff --git a/content/xslt/src/xml/Makefile.in b/content/xslt/src/xml/Makefile.in
index b29b3067caa9..0d726610ca56 100644
--- a/content/xslt/src/xml/Makefile.in
+++ b/content/xslt/src/xml/Makefile.in
@@ -12,6 +12,7 @@ include $(DEPTH)/config/autoconf.mk
 MODULE = transformiix
 LIBRARY_NAME = txxml_s
 LIBXUL_LIBRARY = 1
+FAIL_ON_WARNINGS = 1
 
 CPPSRCS	= \
 	txXMLUtils.cpp \
diff --git a/content/xslt/src/xpath/Makefile.in b/content/xslt/src/xpath/Makefile.in
index 7f9b12a15793..12322ff31504 100644
--- a/content/xslt/src/xpath/Makefile.in
+++ b/content/xslt/src/xpath/Makefile.in
@@ -12,6 +12,7 @@ include $(DEPTH)/config/autoconf.mk
 MODULE = transformiix
 LIBRARY_NAME = txxpath_s
 LIBXUL_LIBRARY = 1
+FAIL_ON_WARNINGS = 1
 
 CPPSRCS = \
         txBooleanExpr.cpp \
diff --git a/content/xslt/src/xslt/Makefile.in b/content/xslt/src/xslt/Makefile.in
index c5c13901f1f9..11b4dfe185f8 100644
--- a/content/xslt/src/xslt/Makefile.in
+++ b/content/xslt/src/xslt/Makefile.in
@@ -12,6 +12,7 @@ include $(DEPTH)/config/autoconf.mk
 MODULE = transformiix
 LIBRARY_NAME = txxslt_s
 LIBXUL_LIBRARY = 1
+FAIL_ON_WARNINGS = 1
 
 CPPSRCS = \
         txNodeSorter.cpp \