diff --git a/m4/curl-functions.m4 b/m4/curl-functions.m4
index 3a27377016..d6671fce94 100644
--- a/m4/curl-functions.m4
+++ b/m4/curl-functions.m4
@@ -1330,36 +1330,36 @@ AC_DEFUN([CURL_CHECK_FUNC_GETADDRINFO], [
   if test "$curl_cv_func_getaddrinfo" = "yes"; then
     AC_MSG_CHECKING([if getaddrinfo is thread-safe])
     if test "$curl_cv_apple" = "yes"; then
-      dnl Darwin 6.0 and macOS 10.2.X and newer
+      dnl Darwin 6.0 and macOS 10.2.x or higher
       tst_tsafe_getaddrinfo="yes"
     fi
     case $host_os in
       aix[[1234]].* | aix5.[[01]].*)
-        dnl AIX 5.1 and older
+        dnl AIX 5.1 or lower
         tst_tsafe_getaddrinfo="no"
         ;;
       aix*)
-        dnl AIX 5.2 and newer
+        dnl AIX 5.2 or higher
         tst_tsafe_getaddrinfo="yes"
         ;;
       darwin[[12345]].*)
-        dnl Darwin 5.0 and macOS 10.1.X and older
+        dnl Darwin 5.0 and macOS 10.1.x or lower
         tst_tsafe_getaddrinfo="no"
         ;;
       freebsd[[1234]].* | freebsd5.[[1234]]*)
-        dnl FreeBSD 5.4 and older
+        dnl FreeBSD 5.4 or lower
         tst_tsafe_getaddrinfo="no"
         ;;
       freebsd*)
-        dnl FreeBSD 5.5 and newer
+        dnl FreeBSD 5.5 or higher
         tst_tsafe_getaddrinfo="yes"
         ;;
       hpux[[123456789]].* | hpux10.* | hpux11.0* | hpux11.10*)
-        dnl HP-UX 11.10 and older
+        dnl HP-UX 11.10 or lower
         tst_tsafe_getaddrinfo="no"
         ;;
       hpux*)
-        dnl HP-UX 11.11 and newer
+        dnl HP-UX 11.11 or higher
         tst_tsafe_getaddrinfo="yes"
         ;;
       midnightbsd*)
@@ -1367,11 +1367,11 @@ AC_DEFUN([CURL_CHECK_FUNC_GETADDRINFO], [
         tst_tsafe_getaddrinfo="yes"
         ;;
       netbsd[[123]].*)
-        dnl NetBSD 3.X and older
+        dnl NetBSD 3.x or lower
         tst_tsafe_getaddrinfo="no"
         ;;
       netbsd*)
-        dnl NetBSD 4.X and newer
+        dnl NetBSD 4.x or higher
         tst_tsafe_getaddrinfo="yes"
         ;;
       *bsd*)
diff --git a/m4/curl-reentrant.m4 b/m4/curl-reentrant.m4
index e77c1cde68..60cd382758 100644
--- a/m4/curl-reentrant.m4
+++ b/m4/curl-reentrant.m4
@@ -303,11 +303,11 @@ dnl Internal macro for CURL_CONFIGURE_THREAD_SAFE.
 AC_DEFUN([CURL_CHECK_NEED_THREAD_SAFE_SYSTEM], [
   case $host_os in
     aix[[123]].* | aix4.[[012]].*)
-      dnl AIX 4.2 and older
+      dnl AIX 4.2 or lower
       tmp_need_thread_safe="no"
       ;;
     aix*)
-      dnl AIX 4.3 and newer
+      dnl AIX 4.3 or higher
       tmp_need_thread_safe="yes"
       ;;
     *)