diff --git a/src/helper.cpp b/src/helper.cpp
index 28921949..eea9e0d3 100644
--- a/src/helper.cpp
+++ b/src/helper.cpp
@@ -280,22 +280,6 @@ std::map <std::string, Color> createTagColorMap (
   return mapping;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-int quantizeTo15Minutes (const int minutes)
-{
-  if (minutes == 0  ||
-      minutes == 15 ||
-      minutes == 45 ||
-      minutes == 60)
-    return minutes;
-
-  auto deviation = minutes % 15;
-  if (deviation < 8)
-    return minutes - deviation;
-
-  return minutes + 15 - deviation;
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 int quantizeToNMinutes (const int minutes, const int N)
 {
diff --git a/src/timew.h b/src/timew.h
index 45c81f1e..2c6129b3 100644
--- a/src/timew.h
+++ b/src/timew.h
@@ -69,7 +69,6 @@ bool expandIntervalHint (const std::string&, Range&);
 std::string jsonFromIntervals (const std::vector <Interval>&);
 Palette createPalette (const Rules&);
 std::map <std::string, Color> createTagColorMap (const Rules&, Palette&, const std::vector <Interval>&);
-int quantizeTo15Minutes (const int);
 int quantizeToNMinutes (const int, const int);
 bool dayIsHoliday (const Rules&, const Datetime&);
 bool findHint (const CLI&, const std::string&);