diff --git a/winsup/mingw/configure b/winsup/mingw/configure
index 3f98db70f..3213c6301 100755
--- a/winsup/mingw/configure
+++ b/winsup/mingw/configure
@@ -757,9 +757,9 @@ echo "$ac_t""$ac_cv_prog_cc_g" 1>&6
   if test "$ac_test_CFLAGS" = set; then
     CFLAGS="$ac_save_CFLAGS"
   elif test $ac_cv_prog_cc_g = yes; then
-    CFLAGS="-g -O2
+    CFLAGS="-g -O2"
   else
-    CFLAGS="-O2
+    CFLAGS="-O2"
   fi
   if test "$ac_test_CXXFLAGS" != set; then
     CXXFLAGS='$(CFLAGS)'
diff --git a/winsup/mingw/configure.in b/winsup/mingw/configure.in
index 2579316e0..2a9b5bab5 100644
--- a/winsup/mingw/configure.in
+++ b/winsup/mingw/configure.in
@@ -47,9 +47,9 @@ dnl normal versions of a library), tasteless as that idea is.
   if test "$ac_test_CFLAGS" = set; then
     CFLAGS="$ac_save_CFLAGS"
   elif test $ac_cv_prog_cc_g = yes; then
-    CFLAGS="-g -O2
+    CFLAGS="-g -O2"
   else
-    CFLAGS="-O2
+    CFLAGS="-O2"
   fi
   if test "$ac_test_CXXFLAGS" != set; then
     CXXFLAGS='$(CFLAGS)'