diff --git a/js/src/old-configure.in b/js/src/old-configure.in
index d01de2c9e360..09caf0be9950 100644
--- a/js/src/old-configure.in
+++ b/js/src/old-configure.in
@@ -799,8 +799,6 @@ case "$target" in
             # warning insists on complaining about the latter case, which
             # is annoying, and rather noisy.
             CXXFLAGS="$CXXFLAGS -Wno-used-but-marked-unused"
-            # We don't worry about backward-compat with C++98.
-            CXXFLAGS="$CXXFLAGS -Wno-c++98-compat -Wno-c++98-compat-pedantic"
         fi
         # make 'foo == bar;' error out
         CFLAGS="$CFLAGS -we4553"
diff --git a/old-configure.in b/old-configure.in
index 7c5faa0ee38e..2ddb378ef6d3 100644
--- a/old-configure.in
+++ b/old-configure.in
@@ -1030,8 +1030,6 @@ case "$target" in
             # warning insists on complaining about the latter case, which
             # is annoying, and rather noisy.
             CXXFLAGS="$CXXFLAGS -Wno-used-but-marked-unused"
-            # We don't worry about backward-compat with C++98.
-            CXXFLAGS="$CXXFLAGS -Wno-c++98-compat -Wno-c++98-compat-pedantic"
         fi
         # make 'foo == bar;' error out
         CFLAGS="$CFLAGS -we4553"