diff --git a/DroidFish/res/values/strings.xml b/DroidFish/res/values/strings.xml
index b28ae83..f0aef07 100644
--- a/DroidFish/res/values/strings.xml
+++ b/DroidFish/res/values/strings.xml
@@ -2,6 +2,7 @@
 <resources>
     <string name="app_name">DroidFish</string>
     <string name="engine_threads_default">1</string>
+    <string name="engine_hash_default">16</string>
     <string name="moves_per_session_default">60</string>
     <string name="time_control_default">120000</string>
     <string name="time_increment_default">0</string>
@@ -220,6 +221,8 @@ you are not actively using the program.\
     <string name="prefs_ponderMode_summary">Let engine think while waiting for opponent\'s move. Supported by most engines.</string>
     <string name="prefs_threads_title">Threads</string>
     <string name="prefs_threads_summary">Number of engine threads (CPU cores) to use. Not supported by all engines.</string>
+    <string name="prefs_hash_title">Hash Table</string>
+    <string name="prefs_hash_summary">Hash table size in megabytes</string>
     <string name="prefs_time_control">Time Control</string>
     <string name="prefs_movesPerSession_title">Moves</string>
     <string name="prefs_movesPerSession_summary">Number of moves between time controls</string>
@@ -364,6 +367,18 @@ you are not actively using the program.\
         <item>3</item>
         <item>4</item>
     </string-array>
+    <string-array name="engine_hash_texts">
+        <item>16 MB</item>
+        <item>32 MB</item>
+        <item>64 MB</item>
+        <item>128 MB</item>
+    </string-array>
+    <string-array name="engine_hash_values">
+        <item>16</item>
+        <item>32</item>
+        <item>64</item>
+        <item>128</item>
+    </string-array>
     <string-array name="moves_per_session_texts">
         <item>Whole Game</item>
         <item>1 move</item>
diff --git a/DroidFish/res/xml/preferences.xml b/DroidFish/res/xml/preferences.xml
index 0141490..da8bf6e 100644
--- a/DroidFish/res/xml/preferences.xml
+++ b/DroidFish/res/xml/preferences.xml
@@ -44,7 +44,15 @@
             android:entries="@array/engine_threads_texts"
             android:defaultValue="@string/engine_threads_default">
         </ListPreference>
-    </PreferenceCategory>
+        <ListPreference
+            android:key="hashMB"
+            android:title="@string/prefs_hash_title"
+            android:summary="@string/prefs_hash_summary"
+            android:entryValues="@array/engine_hash_values"
+            android:entries="@array/engine_hash_texts"
+            android:defaultValue="@string/engine_hash_default">
+        </ListPreference>
+        </PreferenceCategory>
     <PreferenceCategory
         android:title="@string/prefs_time_control">
         <ListPreference
diff --git a/DroidFish/src/org/petero/droidfish/DroidFish.java b/DroidFish/src/org/petero/droidfish/DroidFish.java
index 2ec3c22..dee9ccf 100644
--- a/DroidFish/src/org/petero/droidfish/DroidFish.java
+++ b/DroidFish/src/org/petero/droidfish/DroidFish.java
@@ -149,7 +149,6 @@ public class DroidFish extends Activity implements GUIInterface {
     // FIXME!!! Better behavior if engine is terminated. How exactly?
     // FIXME!!! Handle PGN non-file intents with more than one game.
     // FIXME!!! File load/save of FEN data
-    // FIXME!!! Make engine hash size configurable.
 
     private ChessBoard cb;
     private static DroidChessController ctrl = null;
@@ -191,7 +190,7 @@ public class DroidFish extends Activity implements GUIInterface {
     private final static String gtbDefaultDir = "DroidFish" + File.separator + "gtb";
     private BookOptions bookOptions = new BookOptions();
     private PGNOptions pgnOptions = new PGNOptions();
-    private EGTBOptions egtbOptions = new EGTBOptions();
+    private EngineOptions engineOptions = new EngineOptions();
 
     private long lastVisibleMillis; // Time when GUI became invisible. 0 if currently visible.
     private long lastComputationMillis; // Time when engine last showed that it was computing.
@@ -783,10 +782,11 @@ public class DroidFish extends Activity implements GUIInterface {
         bookOptions.random = (settings.getInt("bookRandom", 500) - 500) * (3.0 / 500);
         setBookOptions();
 
-        egtbOptions.hints = settings.getBoolean("tbHints", false);
-        egtbOptions.hintsEdit = settings.getBoolean("tbHintsEdit", false);
-        egtbOptions.rootProbe = settings.getBoolean("tbRootProbe", true);
-        egtbOptions.engineProbe = settings.getBoolean("tbEngineProbe", true);
+        engineOptions.hashMB = getHashMB();
+        engineOptions.hints = settings.getBoolean("tbHints", false);
+        engineOptions.hintsEdit = settings.getBoolean("tbHintsEdit", false);
+        engineOptions.rootProbe = settings.getBoolean("tbRootProbe", true);
+        engineOptions.engineProbe = settings.getBoolean("tbEngineProbe", true);
         String gtbPath = settings.getString("gtbPath", "");
         gtbPath = gtbPath.trim();
         if (gtbPath.length() == 0) {
@@ -794,8 +794,8 @@ public class DroidFish extends Activity implements GUIInterface {
             String sep = File.separator;
             gtbPath = extDir.getAbsolutePath() + sep + gtbDefaultDir;
         }
-        egtbOptions.gtbPath = gtbPath;
-        setEgtbOptions();
+        engineOptions.gtbPath = gtbPath;
+        setEngineOptions();
         setEgtbHints(cb.getSelectedSquare());
 
         updateThinkingInfo();
@@ -820,6 +820,19 @@ public class DroidFish extends Activity implements GUIInterface {
         ctrl.prefsChanged();
     }
 
+    /** Get hash size in MB from settings, but reduce size to an amount that the device can handle. */
+    private final int getHashMB() {
+        int hashMB = getIntSetting("hashMB", 16);
+        if (hashMB > 16) {
+            int maxMem = (int)(Runtime.getRuntime().maxMemory() / (1024*1024));
+            if (maxMem < 16)
+                maxMem = 16;
+            if (hashMB > maxMem)
+                hashMB = maxMem;
+        }
+        return hashMB;
+    }
+
     private void updateButtons() {
         boolean largeButtons = settings.getBoolean("largeButtons", false);
         Resources r = getResources();
@@ -918,14 +931,14 @@ public class DroidFish extends Activity implements GUIInterface {
 
     private boolean egtbForceReload = false;
 
-    private final void setEgtbOptions() {
-        ctrl.setEgtbOptions(new EGTBOptions(egtbOptions));
-        Probe.getInstance().setPath(egtbOptions.gtbPath, egtbForceReload);
+    private final void setEngineOptions() {
+        ctrl.setEngineOptions(new EngineOptions(engineOptions));
+        Probe.getInstance().setPath(engineOptions.gtbPath, egtbForceReload);
         egtbForceReload = false;
     }
 
     private final void setEgtbHints(int sq) {
-        if (!egtbOptions.hints || (sq < 0)) {
+        if (!engineOptions.hints || (sq < 0)) {
             cb.setSquareDecorations(null);
             return;
         }
diff --git a/DroidFish/src/org/petero/droidfish/EGTBOptions.java b/DroidFish/src/org/petero/droidfish/EngineOptions.java
similarity index 71%
rename from DroidFish/src/org/petero/droidfish/EGTBOptions.java
rename to DroidFish/src/org/petero/droidfish/EngineOptions.java
index 73f902d..d57d2f6 100644
--- a/DroidFish/src/org/petero/droidfish/EGTBOptions.java
+++ b/DroidFish/src/org/petero/droidfish/EngineOptions.java
@@ -1,14 +1,16 @@
 package org.petero.droidfish;
 
-/** Endgame tablebase probing options. */
-public final class EGTBOptions {
+/** Engine options, including endgame tablebase probing options. */
+public final class EngineOptions {
+    public int hashMB;          // Engine hash table size in MB
     public boolean hints;       // Hints when playing/analyzing
     public boolean hintsEdit;   // Hints in "edit board" mode
     public boolean rootProbe;   // Only search optimal moves at root
     public boolean engineProbe; // Let engine use EGTB
     public String gtbPath;      // GTB directory path
 
-    public EGTBOptions() {
+    public EngineOptions() {
+        hashMB = 16;
         hints = false;
         hintsEdit = false;
         rootProbe = false;
@@ -16,7 +18,8 @@ public final class EGTBOptions {
         gtbPath = "";
     }
 
-    public EGTBOptions(EGTBOptions other) {
+    public EngineOptions(EngineOptions other) {
+        hashMB = other.hashMB;
         hints = other.hints;
         hintsEdit = other.hintsEdit;
         rootProbe = other.rootProbe;
@@ -28,9 +31,10 @@ public final class EGTBOptions {
     public boolean equals(Object o) {
         if ((o == null) || (o.getClass() != this.getClass()))
             return false;
-        EGTBOptions other = (EGTBOptions)o;
+        EngineOptions other = (EngineOptions)o;
 
-        return ((hints == other.hints) &&
+        return ((hashMB == other.hashMB) &&
+                (hints == other.hints) &&
                 (hintsEdit == other.hintsEdit) &&
                 (rootProbe == other.rootProbe) &&
                 (engineProbe == other.engineProbe) &&
diff --git a/DroidFish/src/org/petero/droidfish/engine/DroidComputerPlayer.java b/DroidFish/src/org/petero/droidfish/engine/DroidComputerPlayer.java
index 4429ee9..7a4ac11 100644
--- a/DroidFish/src/org/petero/droidfish/engine/DroidComputerPlayer.java
+++ b/DroidFish/src/org/petero/droidfish/engine/DroidComputerPlayer.java
@@ -23,7 +23,7 @@ import java.io.FileReader;
 import java.io.IOException;
 import java.util.ArrayList;
 
-import org.petero.droidfish.EGTBOptions;
+import org.petero.droidfish.EngineOptions;
 import org.petero.droidfish.book.BookOptions;
 import org.petero.droidfish.book.DroidBook;
 import org.petero.droidfish.gamelogic.Move;
@@ -47,7 +47,7 @@ public class DroidComputerPlayer {
     private final Context context;
     private final SearchListener listener;
     private final DroidBook book;
-    private EGTBOptions egtbOptions;
+    private EngineOptions engineOptions;
 
     /** Set when "ucinewgame" needs to be sent. */
     private boolean newGame = false;
@@ -242,7 +242,7 @@ public class DroidComputerPlayer {
         this.context = context;
         this.listener = listener;
         book = DroidBook.getInstance();
-        egtbOptions = new EGTBOptions();
+        engineOptions = new EngineOptions();
         engineState = new EngineState();
         searchRequest = null;
     }
@@ -270,8 +270,8 @@ public class DroidComputerPlayer {
         book.setOptions(options);
     }
 
-    public final void setEgtbOptions(EGTBOptions options) {
-        egtbOptions = options;
+    public final void setEngineOptions(EngineOptions options) {
+        engineOptions = options;
     }
 
     /** Return all book moves, both as a formatted string and as a list of moves. */
@@ -331,7 +331,7 @@ public class DroidComputerPlayer {
     /** Decide what moves to search. Filters out non-optimal moves if tablebases are used. */
     private final ArrayList<Move> movesToSearch(SearchRequest sr) {
         ArrayList<Move> moves = null;
-        if (egtbOptions.rootProbe)
+        if (engineOptions.rootProbe)
             moves = Probe.getInstance().findOptimal(sr.currPos);
         if (moves != null) {
             sr.searchMoves = moves;
@@ -422,9 +422,14 @@ public class DroidComputerPlayer {
     }
 
     private void killOldEngine(String engine) {
-        if (engine.equals(engineState.engine))
-            return;
-        shutdownEngine();
+        boolean needShutDown = !engine.equals(engineState.engine);
+        if (!needShutDown) {
+            UCIEngine uci = uciEngine;
+            if (uci != null)
+                needShutDown = !uci.optionsOk(engineOptions);
+        }
+        if (needShutDown)
+            shutdownEngine();
     }
 
     /** Tell engine to stop searching. */
@@ -662,7 +667,7 @@ public class DroidComputerPlayer {
         switch (engineState.state) {
         case READ_OPTIONS: {
             if (readUCIOption(uci, s)) {
-                uci.initOptions(egtbOptions);
+                uci.initOptions(engineOptions);
                 uci.writeLineToEngine("ucinewgame");
                 uci.writeLineToEngine("isready");
                 engineState.setState(MainState.WAIT_READY);
diff --git a/DroidFish/src/org/petero/droidfish/engine/ExternalEngine.java b/DroidFish/src/org/petero/droidfish/engine/ExternalEngine.java
index 5e82137..42e213a 100644
--- a/DroidFish/src/org/petero/droidfish/engine/ExternalEngine.java
+++ b/DroidFish/src/org/petero/droidfish/engine/ExternalEngine.java
@@ -27,7 +27,7 @@ import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.nio.channels.FileChannel;
 
-import org.petero.droidfish.EGTBOptions;
+import org.petero.droidfish.EngineOptions;
 import org.petero.droidfish.R;
 import android.content.Context;
 
@@ -91,7 +91,9 @@ public class ExternalEngine extends UCIEngineBase {
                 @Override
                 public void run() {
                     try {
-                        engineProc.waitFor();
+                        Process ep = engineProc;
+                        if (ep != null)
+                            ep.waitFor();
                         isRunning = false;
                         if (!startedOk)
                             report.reportError(context.getString(R.string.failed_to_start_engine));
@@ -161,15 +163,34 @@ public class ExternalEngine extends UCIEngineBase {
         }
     }
 
+    private int hashMB = -1;
+    private String gaviotaTbPath = "";
+    private boolean optionsInitialized = false;
+
     /** @inheritDoc */
     @Override
-    public void initOptions(EGTBOptions egtbOptions) {
-        super.initOptions(egtbOptions);
-        setOption("Hash", 16);
-        if (egtbOptions.engineProbe) {
-            setOption("GaviotaTbPath", egtbOptions.gtbPath);
+    public void initOptions(EngineOptions engineOptions) {
+        super.initOptions(engineOptions);
+        hashMB = engineOptions.hashMB;
+        setOption("Hash", engineOptions.hashMB); 
+        if (engineOptions.engineProbe) {
+            gaviotaTbPath = engineOptions.gtbPath;
+            setOption("GaviotaTbPath", engineOptions.gtbPath);
             setOption("GaviotaTbCache", 8);
         }
+        optionsInitialized = true;
+    }
+
+    /** @inheritDoc */
+    @Override
+    public boolean optionsOk(EngineOptions engineOptions) {
+        if (!optionsInitialized)
+            return true;
+        if (hashMB != engineOptions.hashMB)
+            return false;
+        if (haveOption("gaviotatbpath") && !gaviotaTbPath.equals(engineOptions.gtbPath))
+            return false;
+        return true;
     }
 
     /** @inheritDoc */
diff --git a/DroidFish/src/org/petero/droidfish/engine/UCIEngine.java b/DroidFish/src/org/petero/droidfish/engine/UCIEngine.java
index c5bedd5..eb2655f 100644
--- a/DroidFish/src/org/petero/droidfish/engine/UCIEngine.java
+++ b/DroidFish/src/org/petero/droidfish/engine/UCIEngine.java
@@ -18,7 +18,7 @@
 
 package org.petero.droidfish.engine;
 
-import org.petero.droidfish.EGTBOptions;
+import org.petero.droidfish.EngineOptions;
 
 public interface UCIEngine {
 
@@ -32,7 +32,11 @@ public interface UCIEngine {
     public void initialize();
 
     /** Initialize default options. */
-    public void initOptions(EGTBOptions egtbOptions);
+    public void initOptions(EngineOptions engineOptions);
+
+    /** Return true if engine options have correct values.
+     * If false is returned, engine will be restarted. */
+    public boolean optionsOk(EngineOptions engineOptions);
 
     /** Shut down engine. */
     public void shutDown();
diff --git a/DroidFish/src/org/petero/droidfish/engine/UCIEngineBase.java b/DroidFish/src/org/petero/droidfish/engine/UCIEngineBase.java
index e916d75..0bce0ff 100644
--- a/DroidFish/src/org/petero/droidfish/engine/UCIEngineBase.java
+++ b/DroidFish/src/org/petero/droidfish/engine/UCIEngineBase.java
@@ -21,7 +21,7 @@ package org.petero.droidfish.engine;
 import java.util.HashMap;
 import java.util.HashSet;
 
-import org.petero.droidfish.EGTBOptions;
+import org.petero.droidfish.EngineOptions;
 import org.petero.droidfish.engine.cuckoochess.CuckooChessEngine;
 
 import android.content.Context;
@@ -62,7 +62,7 @@ public abstract class UCIEngineBase implements UCIEngine {
     }
 
     @Override
-    public void initOptions(EGTBOptions egtbOptions) {
+    public void initOptions(EngineOptions engineOptions) {
         isUCI = true;
     }
 
@@ -84,6 +84,11 @@ public abstract class UCIEngineBase implements UCIEngine {
         allOptions.add(optName);
     }
 
+    /** Return true if engine has option optName. */
+    protected boolean haveOption(String optName) {
+        return allOptions.contains(optName);
+    }
+
     @Override
     public void setOption(String name, int value) {
         setOption(name, String.format("%d", value));
diff --git a/DroidFish/src/org/petero/droidfish/engine/cuckoochess/CuckooChessEngine.java b/DroidFish/src/org/petero/droidfish/engine/cuckoochess/CuckooChessEngine.java
index 08c06d7..9e62502 100644
--- a/DroidFish/src/org/petero/droidfish/engine/cuckoochess/CuckooChessEngine.java
+++ b/DroidFish/src/org/petero/droidfish/engine/cuckoochess/CuckooChessEngine.java
@@ -25,7 +25,7 @@ import chess.Position;
 import chess.TextIO;
 import java.util.ArrayList;
 
-import org.petero.droidfish.EGTBOptions;
+import org.petero.droidfish.EngineOptions;
 import org.petero.droidfish.engine.LocalPipe;
 import org.petero.droidfish.engine.UCIEngineBase;
 
@@ -74,8 +74,14 @@ public class CuckooChessEngine extends UCIEngineBase {
 
     /** @inheritDoc */
     @Override
-    public final void initOptions(EGTBOptions egtbOptions) {
-        super.initOptions(egtbOptions);
+    public final void initOptions(EngineOptions engineOptions) {
+        super.initOptions(engineOptions);
+    }
+
+    /** @inheritDoc */
+    @Override
+    public boolean optionsOk(EngineOptions engineOptions) {
+        return true;
     }
 
     /** @inheritDoc */
diff --git a/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java b/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java
index 9df68ce..8d2b93e 100644
--- a/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java
+++ b/DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java
@@ -22,7 +22,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 
-import org.petero.droidfish.EGTBOptions;
+import org.petero.droidfish.EngineOptions;
 import org.petero.droidfish.GUIInterface;
 import org.petero.droidfish.GameMode;
 import org.petero.droidfish.PGNOptions;
@@ -42,7 +42,7 @@ public class DroidChessController {
     private DroidComputerPlayer computerPlayer = null;
     private PgnToken.PgnTokenReceiver gameTextListener = null;
     private BookOptions bookOptions = new BookOptions();
-    private EGTBOptions egtbOptions = new EGTBOptions();
+    private EngineOptions engineOptions = new EngineOptions();
     private Game game = null;
     private Move ponderMove = null;
     private GUIInterface gui;
@@ -84,7 +84,7 @@ public class DroidChessController {
         if (computerPlayer == null) {
             computerPlayer = new DroidComputerPlayer(gui.getContext(), listener);
             computerPlayer.setBookOptions(bookOptions);
-            computerPlayer.setEgtbOptions(egtbOptions);
+            computerPlayer.setEngineOptions(engineOptions);
         }
         computerPlayer.queueStartEngine(searchId, engine);
         searchId++;
@@ -152,11 +152,11 @@ public class DroidChessController {
         }
     }
 
-    public final synchronized void setEgtbOptions(EGTBOptions options) {
-        if (!egtbOptions.equals(options)) {
-            egtbOptions = options;
+    public final synchronized void setEngineOptions(EngineOptions options) {
+        if (!engineOptions.equals(options)) {
+            engineOptions = options;
             if (computerPlayer != null)
-                computerPlayer.setEgtbOptions(egtbOptions);
+                computerPlayer.setEngineOptions(engineOptions);
         }
     }