diff --git a/Stage1st/S1Global.h b/Stage1st/S1Global.h
index 88c4075e..b7ebf421 100644
--- a/Stage1st/S1Global.h
+++ b/Stage1st/S1Global.h
@@ -19,6 +19,7 @@
 @property (nonatomic, strong) NSDateFormatter *dateFormatter;
 @property (nonatomic, strong) NSMutableDictionary *dateCache;
 
+- (void)clearCache;
 - (NSString *)headerForDate:(NSDate *)date;
 - (NSComparisonResult)compareDateString:(NSString *)dateString1 withDateString:(NSString *)dateString2;
 
diff --git a/Stage1st/S1Global.m b/Stage1st/S1Global.m
index 091b38cc..d62a4d2c 100644
--- a/Stage1st/S1Global.m
+++ b/Stage1st/S1Global.m
@@ -27,6 +27,10 @@ + (S1Formatter *)sharedInstance
     return myGlobalFormatter;
 }
 
+- (void)clearCache {
+    _dateCache = [[NSMutableDictionary alloc] init];
+}
+
 - (NSDateFormatter *)dateFormatter {
     if (_dateFormatter == nil) {
         _dateFormatter = [[NSDateFormatter alloc] init];
diff --git a/Stage1st/TopicListViewController.swift b/Stage1st/TopicListViewController.swift
index 123a385c..60f21fc6 100644
--- a/Stage1st/TopicListViewController.swift
+++ b/Stage1st/TopicListViewController.swift
@@ -31,6 +31,9 @@ public enum TopicListPresentationType {
 
 extension S1TopicListViewController {
 
+    open override func didReceiveMemoryWarning() {
+        S1Formatter.sharedInstance().clearCache()
+    }
     func isPresentingDatabaseList(_ key: String) -> Bool {
         switch TopicListPresentationType(key: key) {
         case .favorite, .history: