diff --git a/sanoid b/sanoid
index 3aa57a3..ce8207c 100755
--- a/sanoid
+++ b/sanoid
@@ -1519,25 +1519,22 @@ sub convertTimePeriod {
 	my $value=shift;
 	my $period=shift;
 
-	if ($value =~ /^\d+Y$/) {
+	if ($value =~ /^\d+[yY]$/) {
 		$period = 60*60*24*31*365;
 		chop $value;
-	} elsif ($value =~ /^\d+M$/) {
-		$period = 60*60*24*31;
-		chop $value;
-	} elsif ($value =~ /^\d+W$/) {
+	} elsif ($value =~ /^\d+[wW]$/) {
 		$period = 60*60*24*7;
 		chop $value;
-	} elsif ($value =~ /^\d+D$/) {
+	} elsif ($value =~ /^\d+[dD]$/) {
 		$period = 60*60*24;
 		chop $value;
-	} elsif ($value =~ /^\d+h$/) {
+	} elsif ($value =~ /^\d+[hH]$/) {
 		$period = 60*60;
 		chop $value;
-	} elsif ($value =~ /^\d+m$/) {
+	} elsif ($value =~ /^\d+[mM]$/) {
 		$period = 60;
 		chop $value;
-	} elsif ($value =~ /^\d+s$/) {
+	} elsif ($value =~ /^\d+[sS]$/) {
 		$period = 1;
 		chop $value;
 	} elsif ($value =~ /^\d+$/) {
diff --git a/sanoid.defaults.conf b/sanoid.defaults.conf
index 6649c2e..a9ca382 100644
--- a/sanoid.defaults.conf
+++ b/sanoid.defaults.conf
@@ -84,7 +84,8 @@ yearly_min = 0
 # example hourly_warn = 90 means issue WARNING if most recent hourly snapshot is not less than 90 minutes old,
 # daily_crit = 36 means issue CRITICAL if most recent daily snapshot is not less than 36 hours old,
 # monthly_warn = 5 means issue WARNING if most recent monthly snapshot is not less than 5 weeks old... etc.
-# the following time suffixes can also be used: Y = years, M = months, W = weeks, D = days, h = hours, m = minutes, s = seconds
+# the following time case insensitive suffixes can also be used:
+# y = years, w = weeks, d = days, h = hours, m = minutes, s = seconds
 #
 # monitor_dont_warn = yes will cause the monitoring service to report warnings as text, but with status OK.
 # monitor_dont_crit = yes will cause the monitoring service to report criticals as text, but with status OK.
@@ -101,8 +102,8 @@ daily_warn = 28h
 daily_crit = 32h
 weekly_warn = 0
 weekly_crit = 0
-monthly_warn = 32D
-monthly_crit = 40D
+monthly_warn = 32d
+monthly_crit = 40d
 yearly_warn = 0
 yearly_crit = 0