diff --git a/k9mail/src/main/java/com/fsck/k9/K9.java b/k9mail/src/main/java/com/fsck/k9/K9.java
index 586919825..a9ae78d25 100644
--- a/k9mail/src/main/java/com/fsck/k9/K9.java
+++ b/k9mail/src/main/java/com/fsck/k9/K9.java
@@ -4,8 +4,6 @@ package com.fsck.k9;
 
 import java.io.File;
 import java.util.ArrayList;
-import java.util.Calendar;
-import java.util.GregorianCalendar;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -998,41 +996,8 @@ public class K9 extends Application {
             return false;
         }
 
-        GregorianCalendar gregorianCalendar = new GregorianCalendar();
-
-        Integer startHour = Integer.parseInt(mQuietTimeStarts.split(":")[0]);
-        Integer startMinute = Integer.parseInt(mQuietTimeStarts.split(":")[1]);
-        Integer endHour = Integer.parseInt(mQuietTimeEnds.split(":")[0]);
-        Integer endMinute = Integer.parseInt(mQuietTimeEnds.split(":")[1]);
-
-        Integer now = (gregorianCalendar.get(Calendar.HOUR) * 60) + gregorianCalendar.get(Calendar.MINUTE);
-        Integer quietStarts = startHour * 60 + startMinute;
-        Integer quietEnds =  endHour * 60 + endMinute;
-
-        // If start and end times are the same, we're never quiet
-        if (quietStarts.equals(quietEnds)) {
-            return false;
-        }
-
-
-        // 21:00 - 05:00 means we want to be quiet if it's after 9 or before 5
-        if (quietStarts > quietEnds) {
-            // if it's 22:00 or 03:00 but not 8:00
-            if (now >= quietStarts || now <= quietEnds) {
-                return true;
-            }
-        }
-
-        // 01:00 - 05:00
-        else {
-
-            // if it' 2:00 or 4:00 but not 8:00 or 0:00
-            if (now >= quietStarts && now <= quietEnds) {
-                return true;
-            }
-        }
-
-        return false;
+        QuietTimeChecker quietTimeChecker = new QuietTimeChecker(Clock.INSTANCE, mQuietTimeStarts, mQuietTimeEnds);
+        return quietTimeChecker.isQuietTime();
     }
 
     public static void setDebug(boolean debug) {
diff --git a/k9mail/src/main/java/com/fsck/k9/QuietTimeChecker.java b/k9mail/src/main/java/com/fsck/k9/QuietTimeChecker.java
new file mode 100644
index 000000000..23e036019
--- /dev/null
+++ b/k9mail/src/main/java/com/fsck/k9/QuietTimeChecker.java
@@ -0,0 +1,50 @@
+package com.fsck.k9;
+
+
+import java.util.Calendar;
+
+
+class QuietTimeChecker {
+    private final Clock clock;
+    private final int quietTimeStart;
+    private final int quietTimeEnd;
+
+
+    QuietTimeChecker(Clock clock, String quietTimeStart, String quietTimeEnd) {
+        this.clock = clock;
+        this.quietTimeStart = parseTime(quietTimeStart);
+        this.quietTimeEnd = parseTime(quietTimeEnd);
+    }
+
+    private static int parseTime(String time) {
+        String[] parts = time.split(":");
+        int hour = Integer.parseInt(parts[0]);
+        int minute = Integer.parseInt(parts[1]);
+
+        return hour * 60 + minute;
+    }
+
+    public boolean isQuietTime() {
+        // If start and end times are the same, we're never quiet
+        if (quietTimeStart == quietTimeEnd) {
+            return false;
+        }
+
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTimeInMillis(clock.getTime());
+
+        int minutesSinceMidnight = (calendar.get(Calendar.HOUR_OF_DAY) * 60) + calendar.get(Calendar.MINUTE);
+
+        if (quietTimeStart > quietTimeEnd) {
+            if (minutesSinceMidnight >= quietTimeStart || minutesSinceMidnight <= quietTimeEnd) {
+                return true;
+            }
+        } else {
+            if (minutesSinceMidnight >= quietTimeStart && minutesSinceMidnight <= quietTimeEnd) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}
diff --git a/k9mail/src/test/java/com/fsck/k9/QuietTimeCheckerTest.kt b/k9mail/src/test/java/com/fsck/k9/QuietTimeCheckerTest.kt
new file mode 100644
index 000000000..bbb306ae5
--- /dev/null
+++ b/k9mail/src/test/java/com/fsck/k9/QuietTimeCheckerTest.kt
@@ -0,0 +1,121 @@
+package com.fsck.k9
+
+
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.mockito.Mockito.mock
+import java.util.*
+
+
+class QuietTimeCheckerTest {
+    private val clock = mock(Clock::class.java)
+
+    @Test
+    fun endTimeBeforeStartTime_timeIsBeforeEndOfQuietTime() {
+        setClockTo("02:00")
+        val quietTimeChecker = QuietTimeChecker(clock, "22:30", "06:45")
+
+        assertTrue(quietTimeChecker.isQuietTime)
+    }
+
+    @Test
+    fun endTimeBeforeStartTime_timeIsAfterEndOfQuietTime() {
+        setClockTo("10:00")
+        val quietTimeChecker = QuietTimeChecker(clock, "22:30", "06:45")
+
+        assertFalse(quietTimeChecker.isQuietTime)
+    }
+
+    @Test
+    fun endTimeBeforeStartTime_timeIsAfterStartOfQuietTime() {
+        setClockTo("23:00")
+        val quietTimeChecker = QuietTimeChecker(clock, "22:30", "06:45")
+
+        assertTrue(quietTimeChecker.isQuietTime)
+    }
+
+    @Test
+    fun endTimeBeforeStartTime_timeIsStartOfQuietTime() {
+        setClockTo("22:30")
+        val quietTimeChecker = QuietTimeChecker(clock, "22:30", "06:45")
+
+        assertTrue(quietTimeChecker.isQuietTime)
+    }
+
+    @Test
+    fun endTimeBeforeStartTime_timeIsEndOfQuietTime() {
+        setClockTo("06:45")
+        val quietTimeChecker = QuietTimeChecker(clock, "22:30", "06:45")
+
+        assertTrue(quietTimeChecker.isQuietTime)
+    }
+
+    @Test
+    fun startTimeBeforeEndTime_timeIsBeforeStartOfQuietTime() {
+        setClockTo("02:00")
+        val quietTimeChecker = QuietTimeChecker(clock, "09:00", "17:00")
+
+        assertFalse(quietTimeChecker.isQuietTime)
+    }
+
+    @Test
+    fun startTimeBeforeEndTime_timeIsAfterStartOfQuietTime() {
+        setClockTo("10:00")
+        val quietTimeChecker = QuietTimeChecker(clock, "09:00", "17:00")
+
+        assertTrue(quietTimeChecker.isQuietTime)
+    }
+
+    @Test
+    fun startTimeBeforeEndTime_timeIsAfterEndOfQuietTime() {
+        setClockTo("20:00")
+        val quietTimeChecker = QuietTimeChecker(clock, "09:00", "17:00")
+
+        assertFalse(quietTimeChecker.isQuietTime)
+    }
+
+    @Test
+    fun startTimeBeforeEndTime_timeIsStartOfQuietTime() {
+        setClockTo("09:00")
+        val quietTimeChecker = QuietTimeChecker(clock, "09:00", "17:00")
+
+        assertTrue(quietTimeChecker.isQuietTime)
+    }
+
+    @Test
+    fun startTimeBeforeEndTime_timeIsEndOfQuietTime() {
+        setClockTo("17:00")
+        val quietTimeChecker = QuietTimeChecker(clock, "09:00", "17:00")
+
+        assertTrue(quietTimeChecker.isQuietTime)
+    }
+
+    @Test
+    fun startTimeEqualsEndTime_timeIsDifferentFromStartAndEndOfQuietTime_shouldReturnFalse() {
+        setClockTo("10:00")
+        val quietTimeChecker = QuietTimeChecker(clock, "06:00", "06:00")
+
+        assertFalse(quietTimeChecker.isQuietTime)
+    }
+
+    @Test
+    fun startTimeEqualsEndTime_timeIsEqualToStartAndEndOfQuietTime_shouldReturnFalse() {
+        setClockTo("06:00")
+        val quietTimeChecker = QuietTimeChecker(clock, "06:00", "06:00")
+
+        assertFalse(quietTimeChecker.isQuietTime)
+    }
+
+
+    private fun setClockTo(time: String) {
+        val (hourOfDay, minute) = time.split(':').map { it.toInt() }
+
+        val calendar = Calendar.getInstance()
+        calendar.set(Calendar.HOUR_OF_DAY, hourOfDay)
+        calendar.set(Calendar.MINUTE, minute)
+
+        val timeInMillis = calendar.timeInMillis
+        whenever(clock.time).thenReturn(timeInMillis)
+    }
+}