diff --git a/timer_ops_other.go b/timer_ops_other.go
index 546996f..72c2107 100644
--- a/timer_ops_other.go
+++ b/timer_ops_other.go
@@ -10,17 +10,32 @@ import (
 )
 
 func cmdModifyTimer(args []string) int {
+	var err error
 	// If no timer id is specified, edit the most recent one
 	modId := "@0"
 	var tags, remTags, rem []string
 	tags, rem = pullTagsFromArgs(args)
 	remTags, rem = pullRemoveTagsFromArgs(rem)
+	var start, end time.Time
 	for i := range rem {
 		if rem[i][0] == '@' {
 			modId = rem[i]
 		}
-		if strings.HasPrefix(rem, "start:") {
-
+		if strings.HasPrefix(rem[i], "start:") {
+			stStr := strings.TrimPrefix(rem[i], "start:")
+			start, err = parseFuzzyTime(stStr)
+			if err != nil {
+				fmt.Println("Unable to parse start time: " + stStr)
+				return 1
+			}
+		}
+		if strings.HasPrefix(rem[i], "end:") {
+			endStr := strings.TrimPrefix(rem[i], "end:")
+			end, err = parseFuzzyTime(endStr)
+			if err != nil {
+				fmt.Println("Unable to parse end time: " + endStr)
+				return 1
+			}
 		}
 	}
 	timerId, err := strconv.Atoi(modId[1:])
@@ -39,6 +54,20 @@ func cmdModifyTimer(args []string) int {
 	for i := range remTags {
 		tmr.RemoveTag(remTags[i])
 	}
+	if !start.IsZero() {
+		// TODO: Fix keying by start time
+		fmt.Println("Not supported")
+		return 1
+		//tmr.SetStart(start)
+	}
+	if tmr.GetEnd().IsZero() {
+		// At this point, timers must be stopped to modify the end date
+		fmt.Println("Timer has not been stopped. Cowardly refusing to modify stop time.")
+		return 1
+	}
+	if !end.IsZero() {
+		tmr.SetEnd(end)
+	}
 	if err = gdb.SaveTimeEntry(tmr); err != nil {
 		fmt.Println("Error saving modified timer:", err.Error())
 		return 1