diff --git a/packages/SystemUI/src/com/android/systemui/accessibility/fontscaling/FontScalingDialog.kt b/packages/SystemUI/src/com/android/systemui/accessibility/fontscaling/FontScalingDialog.kt
index 1836ce8577835..1cdd5801b57dc 100644
--- a/packages/SystemUI/src/com/android/systemui/accessibility/fontscaling/FontScalingDialog.kt
+++ b/packages/SystemUI/src/com/android/systemui/accessibility/fontscaling/FontScalingDialog.kt
@@ -84,31 +84,41 @@ class FontScalingDialog(
 
         seekBarWithIconButtonsView.setOnSeekBarChangeListener(
             object : OnSeekBarChangeListener {
+                var isTrackingTouch = false
+
                 override fun onProgressChanged(seekBar: SeekBar, progress: Int, fromUser: Boolean) {
-                    if (progress != lastProgress) {
-                        if (!fontSizeHasBeenChangedFromTile) {
-                            backgroundExecutor.execute { updateSecureSettingsIfNeeded() }
-                            fontSizeHasBeenChangedFromTile = true
-                        }
-
-                        backgroundExecutor.execute { updateFontScale(strEntryValues[progress]) }
-
-                        lastProgress = progress
+                    if (!isTrackingTouch) {
+                        // The seekbar progress is changed by icon buttons
+                        changeFontSize(progress)
                     }
                 }
 
                 override fun onStartTrackingTouch(seekBar: SeekBar) {
-                    // Do nothing
+                    isTrackingTouch = true
                 }
 
                 override fun onStopTrackingTouch(seekBar: SeekBar) {
-                    // Do nothing
+                    isTrackingTouch = false
+                    changeFontSize(seekBar.progress)
                 }
             }
         )
         doneButton.setOnClickListener { dismiss() }
     }
 
+    private fun changeFontSize(progress: Int) {
+        if (progress != lastProgress) {
+            if (!fontSizeHasBeenChangedFromTile) {
+                backgroundExecutor.execute { updateSecureSettingsIfNeeded() }
+                fontSizeHasBeenChangedFromTile = true
+            }
+
+            backgroundExecutor.execute { updateFontScale(strEntryValues[progress]) }
+
+            lastProgress = progress
+        }
+    }
+
     private fun fontSizeValueToIndex(value: Float): Int {
         var lastValue = strEntryValues[0].toFloat()
         for (i in 1 until strEntryValues.size) {
diff --git a/packages/SystemUI/tests/src/com/android/systemui/accessibility/fontscaling/FontScalingDialogTest.kt b/packages/SystemUI/tests/src/com/android/systemui/accessibility/fontscaling/FontScalingDialogTest.kt
index eb8295653199e..a6dcd24371d56 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/accessibility/fontscaling/FontScalingDialogTest.kt
+++ b/packages/SystemUI/tests/src/com/android/systemui/accessibility/fontscaling/FontScalingDialogTest.kt
@@ -26,6 +26,8 @@ import com.android.systemui.R
 import com.android.systemui.SysuiTestCase
 import com.android.systemui.common.ui.view.SeekBarWithIconButtonsView
 import com.android.systemui.util.concurrency.FakeExecutor
+import com.android.systemui.util.mockito.capture
+import com.android.systemui.util.mockito.whenever
 import com.android.systemui.util.settings.FakeSettings
 import com.android.systemui.util.settings.SecureSettings
 import com.android.systemui.util.settings.SystemSettings
@@ -34,6 +36,10 @@ import com.google.common.truth.Truth.assertThat
 import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
+import org.mockito.ArgumentCaptor
+import org.mockito.Captor
+import org.mockito.Mockito.spy
+import org.mockito.Mockito.verify
 import org.mockito.MockitoAnnotations
 
 private const val ON: Int = 1
@@ -53,6 +59,9 @@ class FontScalingDialogTest : SysuiTestCase() {
             .getResources()
             .getStringArray(com.android.settingslib.R.array.entryvalues_font_size)
 
+    @Captor
+    private lateinit var seekBarChangeCaptor: ArgumentCaptor<SeekBar.OnSeekBarChangeListener>
+
     @Before
     fun setUp() {
         MockitoAnnotations.initMocks(this)
@@ -61,7 +70,7 @@ class FontScalingDialogTest : SysuiTestCase() {
         secureSettings = FakeSettings()
         backgroundExecutor = FakeExecutor(FakeSystemClock())
         fontScalingDialog =
-            FontScalingDialog(mContext, systemSettings, secureSettings, backgroundExecutor)
+            spy(FontScalingDialog(mContext, systemSettings, secureSettings, backgroundExecutor))
     }
 
     @Test
@@ -70,7 +79,7 @@ class FontScalingDialogTest : SysuiTestCase() {
 
         val seekBar: SeekBar = fontScalingDialog.findViewById<SeekBar>(R.id.seekbar)!!
         val progress: Int = seekBar.getProgress()
-        val currentScale = systemSettings.getFloat(Settings.System.FONT_SCALE, /* def = */ 1.0f)
+        val currentScale = systemSettings.getFloat(Settings.System.FONT_SCALE, /* def= */ 1.0f)
 
         assertThat(currentScale).isEqualTo(fontSizeValueArray[progress].toFloat())
 
@@ -91,7 +100,7 @@ class FontScalingDialogTest : SysuiTestCase() {
         iconEndFrame.performClick()
         backgroundExecutor.runAllReady()
 
-        val currentScale = systemSettings.getFloat(Settings.System.FONT_SCALE, /* def = */ 1.0f)
+        val currentScale = systemSettings.getFloat(Settings.System.FONT_SCALE, /* def= */ 1.0f)
         assertThat(seekBar.getProgress()).isEqualTo(1)
         assertThat(currentScale).isEqualTo(fontSizeValueArray[1].toFloat())
 
@@ -112,7 +121,7 @@ class FontScalingDialogTest : SysuiTestCase() {
         iconStartFrame.performClick()
         backgroundExecutor.runAllReady()
 
-        val currentScale = systemSettings.getFloat(Settings.System.FONT_SCALE, /* def = */ 1.0f)
+        val currentScale = systemSettings.getFloat(Settings.System.FONT_SCALE, /* def= */ 1.0f)
         assertThat(seekBar.getProgress()).isEqualTo(fontSizeValueArray.size - 2)
         assertThat(currentScale)
             .isEqualTo(fontSizeValueArray[fontSizeValueArray.size - 2].toFloat())
@@ -141,4 +150,39 @@ class FontScalingDialogTest : SysuiTestCase() {
 
         fontScalingDialog.dismiss()
     }
+
+    @Test
+    fun dragSeekbar_systemFontSizeSettingsDoesNotChange() {
+        val slider: SeekBarWithIconButtonsView = spy(SeekBarWithIconButtonsView(mContext))
+        whenever(
+                fontScalingDialog.findViewById<SeekBarWithIconButtonsView>(R.id.font_scaling_slider)
+            )
+            .thenReturn(slider)
+        fontScalingDialog.show()
+        verify(slider).setOnSeekBarChangeListener(capture(seekBarChangeCaptor))
+        val seekBar: SeekBar = slider.findViewById(R.id.seekbar)!!
+
+        // Default seekbar progress for font size is 1, simulate dragging to 0 without
+        // releasing the finger.
+        seekBarChangeCaptor.value.onStartTrackingTouch(seekBar)
+        // Update seekbar progress. This will trigger onProgressChanged in the
+        // OnSeekBarChangeListener and the seekbar could get updated progress value
+        // in onStopTrackingTouch.
+        seekBar.progress = 0
+        backgroundExecutor.runAllReady()
+
+        // Verify that the scale of font size remains the default value 1.0f.
+        var systemScale = systemSettings.getFloat(Settings.System.FONT_SCALE, /* def= */ 1.0f)
+        assertThat(systemScale).isEqualTo(1.0f)
+
+        // Simulate releasing the finger from the seekbar.
+        seekBarChangeCaptor.value.onStopTrackingTouch(seekBar)
+        backgroundExecutor.runAllReady()
+
+        // Verify that the scale of font size has been updated.
+        systemScale = systemSettings.getFloat(Settings.System.FONT_SCALE, /* def= */ 1.0f)
+        assertThat(systemScale).isEqualTo(fontSizeValueArray[0].toFloat())
+
+        fontScalingDialog.dismiss()
+    }
 }