diff --git a/src/bitcoinrpc.cpp b/src/bitcoinrpc.cpp
index 02a2f8cddef..36490e94f71 100644
--- a/src/bitcoinrpc.cpp
+++ b/src/bitcoinrpc.cpp
@@ -1403,7 +1403,7 @@ void ThreadTopUpKeyPool(void* parg)
 
 void ThreadCleanWalletPassphrase(void* parg)
 {
-    int64 nMyWakeTime = GetTimeMillis() + *((int*)parg) * 1000;
+    int64 nMyWakeTime = GetTimeMillis() + *((int64*)parg) * 1000;
 
     ENTER_CRITICAL_SECTION(cs_nWalletUnlockTime);
 
@@ -1439,7 +1439,7 @@ void ThreadCleanWalletPassphrase(void* parg)
 
     LEAVE_CRITICAL_SECTION(cs_nWalletUnlockTime);
 
-    delete (int*)parg;
+    delete (int64*)parg;
 }
 
 Value walletpassphrase(const Array& params, bool fHelp)
@@ -1474,7 +1474,7 @@ Value walletpassphrase(const Array& params, bool fHelp)
             "Stores the wallet decryption key in memory for <timeout> seconds.");
 
     CreateThread(ThreadTopUpKeyPool, NULL);
-    int* pnSleepTime = new int(params[1].get_int());
+    int64* pnSleepTime = new int64(params[1].get_int64());
     CreateThread(ThreadCleanWalletPassphrase, pnSleepTime);
 
     return Value::null;
diff --git a/src/util.h b/src/util.h
index 19a291209ae..34ccecac75a 100644
--- a/src/util.h
+++ b/src/util.h
@@ -115,7 +115,9 @@ typedef u_int SOCKET;
 #define Beep(n1,n2)         (0)
 inline void Sleep(int64 n)
 {
-    boost::thread::sleep(boost::get_system_time() + boost::posix_time::milliseconds(n));
+    /*Boost has a year 2038 problem— if the request sleep time is past epoch+2^31 seconds the sleep returns instantly.
+      So we clamp our sleeps here to 10 years and hope that boost is fixed by 2028.*/
+    boost::thread::sleep(boost::get_system_time() + boost::posix_time::milliseconds(n>315576000000LL?315576000000LL:n));
 }
 #endif