diff --git a/core/java/android/app/AlarmManager.java b/core/java/android/app/AlarmManager.java
index ae8a2cbf51206..b3137d84c3f19 100644
--- a/core/java/android/app/AlarmManager.java
+++ b/core/java/android/app/AlarmManager.java
@@ -36,7 +36,6 @@ import android.util.proto.ProtoOutputStream;
 
 import libcore.timezone.ZoneInfoDb;
 
-import java.io.IOException;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.ref.WeakReference;
@@ -996,12 +995,7 @@ public class AlarmManager {
 
         // Reject this timezone if it isn't an Olson zone we recognize.
         if (mTargetSdkVersion >= Build.VERSION_CODES.M) {
-            boolean hasTimeZone = false;
-            try {
-                hasTimeZone = ZoneInfoDb.getInstance().hasTimeZone(timeZone);
-            } catch (IOException ignored) {
-            }
-
+            boolean hasTimeZone = ZoneInfoDb.getInstance().hasTimeZone(timeZone);
             if (!hasTimeZone) {
                 throw new IllegalArgumentException("Timezone: " + timeZone + " is not an Olson ID");
             }
diff --git a/core/java/android/text/format/Time.java b/core/java/android/text/format/Time.java
index 49cebc1416363..f1a8565efde15 100644
--- a/core/java/android/text/format/Time.java
+++ b/core/java/android/text/format/Time.java
@@ -21,7 +21,6 @@ import android.util.TimeFormatException;
 import libcore.timezone.ZoneInfoDb;
 import libcore.util.ZoneInfo;
 
-import java.io.IOException;
 import java.util.Locale;
 import java.util.TimeZone;
 
@@ -1117,19 +1116,14 @@ public class Time {
         }
 
         private static ZoneInfo lookupZoneInfo(String timezoneId) {
-            try {
-                ZoneInfo zoneInfo = ZoneInfoDb.getInstance().makeTimeZone(timezoneId);
-                if (zoneInfo == null) {
-                    zoneInfo = ZoneInfoDb.getInstance().makeTimeZone("GMT");
-                }
-                if (zoneInfo == null) {
-                    throw new AssertionError("GMT not found: \"" + timezoneId + "\"");
-                }
-                return zoneInfo;
-            } catch (IOException e) {
-                // This should not ever be thrown.
-                throw new AssertionError("Error loading timezone: \"" + timezoneId + "\"", e);
+            ZoneInfo zoneInfo = ZoneInfoDb.getInstance().makeTimeZone(timezoneId);
+            if (zoneInfo == null) {
+                zoneInfo = ZoneInfoDb.getInstance().makeTimeZone("GMT");
             }
+            if (zoneInfo == null) {
+                throw new AssertionError("GMT not found: \"" + timezoneId + "\"");
+            }
+            return zoneInfo;
         }
 
         public void switchTimeZone(String timezone) {
diff --git a/services/java/com/android/server/SystemServer.java b/services/java/com/android/server/SystemServer.java
index ab84c3653f5f6..20fc272e4e2e4 100644
--- a/services/java/com/android/server/SystemServer.java
+++ b/services/java/com/android/server/SystemServer.java
@@ -180,6 +180,8 @@ import com.android.server.wm.ActivityTaskManagerService;
 import com.android.server.wm.WindowManagerGlobalLock;
 import com.android.server.wm.WindowManagerService;
 
+import libcore.timezone.ZoneInfoDb;
+
 import dalvik.system.VMRuntime;
 
 import com.google.android.startop.iorap.IorapForwardingService;
@@ -438,8 +440,9 @@ public final class SystemServer {
             // Default the timezone property to GMT if not set.
             //
             String timezoneProperty = SystemProperties.get("persist.sys.timezone");
-            if (timezoneProperty == null || timezoneProperty.isEmpty()) {
-                Slog.w(TAG, "Timezone not set; setting to GMT.");
+            if (!isValidTimeZoneId(timezoneProperty)) {
+                Slog.w(TAG, "persist.sys.timezone is not valid (" + timezoneProperty
+                        + "); setting to GMT.");
                 SystemProperties.set("persist.sys.timezone", "GMT");
             }
 
@@ -617,6 +620,12 @@ public final class SystemServer {
         throw new RuntimeException("Main thread loop unexpectedly exited");
     }
 
+    private static boolean isValidTimeZoneId(String timezoneProperty) {
+        return timezoneProperty != null
+                && !timezoneProperty.isEmpty()
+                && ZoneInfoDb.getInstance().hasTimeZone(timezoneProperty);
+    }
+
     private boolean isFirstBootOrUpgrade() {
         return mPackageManagerService.isFirstBoot() || mPackageManagerService.isDeviceUpgrading();
     }