diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/HeadsUpTouchHelper.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/HeadsUpTouchHelper.java
index dd200da..b26cb259 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/HeadsUpTouchHelper.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/HeadsUpTouchHelper.java
@@ -111,8 +111,9 @@
                     mInitialTouchY = y;
                     int startHeight = (int) (mPickedChild.getActualHeight()
                                                 + mPickedChild.getTranslationY());
-                    mPanel.setPanelScrimMinFraction((float) startHeight
-                            / mPanel.getMaxPanelHeight());
+                    float maxPanelHeight = mPanel.getMaxPanelHeight();
+                    mPanel.setPanelScrimMinFraction(maxPanelHeight > 0f
+                            ? (float) startHeight / maxPanelHeight : 0f);
                     mPanel.startExpandMotion(x, y, true /* startTracking */, startHeight);
                     mPanel.startExpandingFromPeek();
                     // This call needs to be after the expansion start otherwise we will get a
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
index 6bc0cf6..2a50444 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
@@ -2074,7 +2074,7 @@
         } else {
             maxHeight = calculatePanelHeightShade();
         }
-        maxHeight = Math.max(maxHeight, min);
+        maxHeight = Math.max(min, maxHeight);
         return maxHeight;
     }
 
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PanelBar.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PanelBar.java
index 063d00b..21a9667 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PanelBar.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PanelBar.java
@@ -16,6 +16,8 @@
 
 package com.android.systemui.statusbar.phone;
 
+import static java.lang.Float.isNaN;
+
 import android.content.Context;
 import android.os.Bundle;
 import android.os.Parcelable;
@@ -160,6 +162,9 @@
      *                 fraction as the panel also might be expanded if the fraction is 0
      */
     public void panelExpansionChanged(float frac, boolean expanded) {
+        if (isNaN(frac)) {
+            throw new IllegalArgumentException("frac cannot be NaN");
+        }
         boolean fullyClosed = true;
         boolean fullyOpened = false;
         if (SPEW) LOG("panelExpansionChanged: start state=%d", mState);
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarView.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarView.java
index 2835201..3d705da 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarView.java
@@ -21,6 +21,8 @@
 import static com.android.systemui.ScreenDecorations.DisplayCutoutView.boundsFromDirection;
 import static com.android.systemui.SysUiServiceProvider.getComponent;
 
+import static java.lang.Float.isNaN;
+
 import android.annotation.Nullable;
 import android.content.Context;
 import android.content.res.Configuration;
@@ -265,6 +267,9 @@
 
     @Override
     public void panelScrimMinFractionChanged(float minFraction) {
+        if (isNaN(minFraction)) {
+            throw new IllegalArgumentException("minFraction cannot be NaN");
+        }
         if (mMinFraction != minFraction) {
             mMinFraction = minFraction;
             updateScrimFraction();