diff --git a/lib/get_next_level b/lib/get_next_level
index 973318d..c53894a 100644
--- a/lib/get_next_level
+++ b/lib/get_next_level
@@ -21,8 +21,8 @@ get_next_level() {
 			nextlevels[level]=$timestamp
 		done
 	} < <(
-		rrdtool graph /dev/null -s ${first["time"]%:} -e +15y	\
-			DEF:data=$rrdfile:AP:AVERAGE:step=600		\
+		rrdtool graph /dev/null -s -$prevperiod -e +5y	\
+			DEF:data=$rrdfile:AP:AVERAGE:step=3600		\
 			VDEF:intercept=data,LSLINT			\
 			VDEF:growth=data,LSLSLOPE			\
 			CDEF:trend=data,POP,COUNT,growth,*,intercept,+	\
@@ -96,7 +96,7 @@ get_next_level() {
 				esac
 			done
 		} < <(
-			rrdtool graph /dev/null -s ${first["time"]%:} -e +15y	\
+			rrdtool graph /dev/null -s -$prevperiod -e +5y	\
 				DEF:data=$rrdfile:$stat:AVERAGE:step=600	\
 				VDEF:intercept=data,LSLINT			\
 				VDEF:growth=data,LSLSLOPE			\
diff --git a/settings b/settings
index 7af1b91..b2ee412 100644
--- a/settings
+++ b/settings
@@ -29,7 +29,7 @@ L14color=8B1479
 L15color=6B127D
 L16color=591494
 
-default_prevperiod=1m
+default_prevperiod=1month
 now=$(date +%s)
 
 (( default_start = now - 604800 ))