diff --git a/app/common/timerange.cpp b/app/common/timerange.cpp
index 67ac3f391..cd99a1bd4 100644
--- a/app/common/timerange.cpp
+++ b/app/common/timerange.cpp
@@ -104,6 +104,34 @@ TimeRange TimeRange::Combine(const TimeRange &a, const TimeRange &b)
                    qMax(a.out(), b.out()));
 }
 
+TimeRange TimeRange::operator+(const rational &rhs) const
+{
+  TimeRange answer(*this);
+  answer += rhs;
+  return answer;
+}
+
+TimeRange TimeRange::operator-(const rational &rhs) const
+{
+  TimeRange answer(*this);
+  answer -= rhs;
+  return answer;
+}
+
+const TimeRange &TimeRange::operator+=(const rational &rhs)
+{
+  set_range(in_ + rhs, out_ + rhs);
+
+  return *this;
+}
+
+const TimeRange &TimeRange::operator-=(const rational &rhs)
+{
+  set_range(in_ - rhs, out_ - rhs);
+
+  return *this;
+}
+
 void TimeRange::normalize()
 {
   // If `out` is earlier than `in`, swap them
@@ -173,7 +201,7 @@ bool TimeRangeList::ContainsTimeRange(const TimeRange &range, bool in_inclusive,
   return false;
 }
 
-TimeRangeList TimeRangeList::Intersects(const TimeRange &range)
+TimeRangeList TimeRangeList::Intersects(const TimeRange &range) const
 {
   TimeRangeList intersect_list;
 
diff --git a/app/common/timerange.h b/app/common/timerange.h
index 5daeba390..41d7c4026 100644
--- a/app/common/timerange.h
+++ b/app/common/timerange.h
@@ -47,6 +47,12 @@ public:
   TimeRange CombineWith(const TimeRange& a) const;
   static TimeRange Combine(const TimeRange &a, const TimeRange &b);
 
+  TimeRange operator+(const rational& rhs) const;
+  TimeRange operator-(const rational& rhs) const;
+
+  const TimeRange& operator+=(const rational &rhs);
+  const TimeRange& operator-=(const rational &rhs);
+
 private:
   void normalize();
 
@@ -66,7 +72,7 @@ public:
 
   bool ContainsTimeRange(const TimeRange& range, bool in_inclusive = true, bool out_inclusive = true) const;
 
-  TimeRangeList Intersects(const TimeRange& range);
+  TimeRangeList Intersects(const TimeRange& range) const;
 
 private:
   void PrintTimeList();