diff --git a/configure.in b/configure.in
index 302e4ee0fab..794fae42135 100644
--- a/configure.in
+++ b/configure.in
@@ -655,9 +655,9 @@ case "$target" in
         fi
         if test "$_CC_MAJOR_VERSION" = "13"; then
             _CC_SUITE=7
-            CXXFLAGS="$CXXFLAGS -Zc:wchar_t"
         elif test "$_CC_MAJOR_VERSION" = "14"; then
             _CC_SUITE=8
+            CXXFLAGS="$CXXFLAGS -Zc:wchar_t-"
             dnl -DYNAMICBASE is only supported on VC8SP1 or newer,
             dnl so be very specific here!
             dnl VC8 is 14.00.50727.42, VC8SP1 is 14.00.50727.762
@@ -670,11 +670,13 @@ case "$target" in
             AC_DEFINE(_CRT_NONSTDC_NO_DEPRECATE)
         elif test "$_CC_MAJOR_VERSION" = "15"; then
             _CC_SUITE=9
+            CXXFLAGS="$CXXFLAGS -Zc:wchar_t-"
             _USE_DYNAMICBASE=1
             AC_DEFINE(_CRT_SECURE_NO_WARNINGS)
             AC_DEFINE(_CRT_NONSTDC_NO_WARNINGS)
         elif test "$_CC_MAJOR_VERSION" = "16"; then
             _CC_SUITE=10
+            CXXFLAGS="$CXXFLAGS -Zc:wchar_t-"
             _USE_DYNAMICBASE=1
             AC_DEFINE(_CRT_SECURE_NO_WARNINGS)
             AC_DEFINE(_CRT_NONSTDC_NO_WARNINGS)
diff --git a/js/src/configure.in b/js/src/configure.in
index 58c6fb31f11..169ac841458 100644
--- a/js/src/configure.in
+++ b/js/src/configure.in
@@ -555,9 +555,9 @@ case "$target" in
         fi
         if test "$_CC_MAJOR_VERSION" = "13"; then
             _CC_SUITE=7
-            CXXFLAGS="$CXXFLAGS -Zc:wchar_t"
         elif test "$_CC_MAJOR_VERSION" = "14"; then
             _CC_SUITE=8
+            CXXFLAGS="$CXXFLAGS -Zc:wchar_t-"
             dnl -DYNAMICBASE is only supported on VC8SP1 or newer,
             dnl so be very specific here!
             dnl VC8 is 14.00.50727.42, VC8SP1 is 14.00.50727.762
@@ -570,11 +570,13 @@ case "$target" in
             AC_DEFINE(_CRT_NONSTDC_NO_DEPRECATE)
         elif test "$_CC_MAJOR_VERSION" = "15"; then
             _CC_SUITE=9
+            CXXFLAGS="$CXXFLAGS -Zc:wchar_t-"
             _USE_DYNAMICBASE=1
             AC_DEFINE(_CRT_SECURE_NO_WARNINGS)
             AC_DEFINE(_CRT_NONSTDC_NO_WARNINGS)
         elif test "$_CC_MAJOR_VERSION" = "16"; then
             _CC_SUITE=10
+            CXXFLAGS="$CXXFLAGS -Zc:wchar_t-"
             _USE_DYNAMICBASE=1
             AC_DEFINE(_CRT_SECURE_NO_WARNINGS)
             AC_DEFINE(_CRT_NONSTDC_NO_WARNINGS)