diff --git a/res/values-ru/text_strings.xml b/res/values-ru/text_strings.xml
index 62619a59..b94f07cd 100644
--- a/res/values-ru/text_strings.xml
+++ b/res/values-ru/text_strings.xml
@@ -45,6 +45,8 @@
 	<string name="c_calc_science_notation_title">Результат в научной форме</string>
 	<string name="c_calc_science_notation_summary">Если включено - результат будет всегда записан в научной форме (12.34E-12)</string>
 	<string name="p_calc_result_precision_title">Точность результата</string>
+	<string name="p_calc_max_calculation_time_title">Максимальное время вычисления</string>
+	<string name="p_calc_max_calculation_time_summary">Если вычисления превысят установленный предел - калькулятор остановится с ошибкой</string>
 	<string name="c_exit">Выход</string>
 	<string name="c_add">Добавить</string>
 	<string name="c_cancel">Отмена</string>
diff --git a/res/values/preferences.xml b/res/values/preferences.xml
index cc02369c..96e357f0 100644
--- a/res/values/preferences.xml
+++ b/res/values/preferences.xml
@@ -18,6 +18,9 @@
 	<string name="p_calc_result_precision_key">org.solovyev.android.calculator.CalculatorModel_result_precision</string>
 	<string name="p_calc_result_precision">5</string>
 
+	<string name="p_calc_max_calculation_time_key">calculation.max_calculation_time</string>
+	<string name="p_calc_max_calculation_time">5</string>
+
 	<string name="p_calc_color_display_key">org.solovyev.android.calculator.CalculatorModel_color_display</string>
 	<string name="p_calc_color_display">true</string>
 
diff --git a/res/values/text_strings.xml b/res/values/text_strings.xml
index 5c54c916..41ca065f 100644
--- a/res/values/text_strings.xml
+++ b/res/values/text_strings.xml
@@ -45,6 +45,8 @@
 	<string name="c_calc_science_notation_title">Always scientific notation</string>
 	<string name="c_calc_science_notation_summary">If turned on forces to use only scientific notation of output (12.34E-12)</string>
 	<string name="p_calc_result_precision_title">Precision of result</string>
+	<string name="p_calc_max_calculation_time_title">Maximum calculation time</string>
+	<string name="p_calc_max_calculation_time_summary">If calculations exceed specified limit - calculator halts with error</string>
 	<string name="c_exit">Exit</string>
 	<string name="c_add">Add</string>
 	<string name="c_cancel">Cancel</string>
diff --git a/res/xml/preferences.xml b/res/xml/preferences.xml
index ef3d6ce1..4a64e430 100644
--- a/res/xml/preferences.xml
+++ b/res/xml/preferences.xml
@@ -53,6 +53,13 @@
 						a:summary="@string/c_numeral_bases_summary"
 						a:entryValues="@array/p_numeral_bases"/>
 
+		<org.solovyev.android.prefs.NumberPickerDialogPreference
+				a:key="@string/p_calc_max_calculation_time_key"
+				a:title="@string/p_calc_max_calculation_time_title"
+				a:summary="@string/p_calc_max_calculation_time_summary"
+				a:defaultValue="5"
+				range:boundaries="3;1000"/>
+
 	</PreferenceScreen>
 
 	<PreferenceScreen
diff --git a/src/main/java/org/solovyev/android/calculator/CalculatorActivity.java b/src/main/java/org/solovyev/android/calculator/CalculatorActivity.java
index 845d5838..82a96766 100644
--- a/src/main/java/org/solovyev/android/calculator/CalculatorActivity.java
+++ b/src/main/java/org/solovyev/android/calculator/CalculatorActivity.java
@@ -793,7 +793,7 @@ public class CalculatorActivity extends Activity implements FontSizeAdjuster, Sh
 
 		if (CalculatorEngine.Preferences.getPreferenceKeys().contains(key)) {
 			CalculatorEngine.instance.softReset(this, preferences);
-			this.calculatorModel.evaluate();
+			//this.calculatorModel.evaluate();
 		}
 
 		if ( USE_BACK_AS_PREV_P_KEY.equals(key) ) {
diff --git a/src/main/java/org/solovyev/android/calculator/model/CalculatorEngine.java b/src/main/java/org/solovyev/android/calculator/model/CalculatorEngine.java
index ddd7b2b9..d6d50ec3 100644
--- a/src/main/java/org/solovyev/android/calculator/model/CalculatorEngine.java
+++ b/src/main/java/org/solovyev/android/calculator/model/CalculatorEngine.java
@@ -47,6 +47,9 @@ public enum CalculatorEngine {
 	private static final String MULTIPLICATION_SIGN_P_KEY = "org.solovyev.android.calculator.CalculatorActivity_calc_multiplication_sign";
 	private static final String MULTIPLICATION_SIGN_DEFAULT = "×";
 
+	private static final String MAX_CALCULATION_TIME_P_KEY = "calculation.max_calculation_time";
+	private static final String MAX_CALCULATION_TIME_DEFAULT = "5";
+
 	private static final String SCIENCE_NOTATION_P_KEY = "calculation.output.science_notation";
 	private static final boolean SCIENCE_NOTATION_DEFAULT = false;
 
@@ -70,6 +73,7 @@ public enum CalculatorEngine {
 		public static final Preference<NumeralBase> numeralBase = StringPreference.newInstance(NUMERAL_BASES_P_KEY, NUMERAL_BASES_DEFAULT, EnumMapper.newInstance(NumeralBase.class));
 		public static final Preference<AngleUnit> angleUnit = StringPreference.newInstance(ANGLE_UNITS_P_KEY, ANGLE_UNITS_DEFAULT, EnumMapper.newInstance(AngleUnit.class));
 		public static final Preference<Boolean> scienceNotation = new BooleanPreference(SCIENCE_NOTATION_P_KEY, SCIENCE_NOTATION_DEFAULT);
+		public static final Preference<Integer> maxCalculationTime = StringPreference.newInstance(MAX_CALCULATION_TIME_P_KEY, MAX_CALCULATION_TIME_DEFAULT, new NumberMapper<Integer>(Integer.class));
 
 		private static final List<String> preferenceKeys = new ArrayList<String>();
 
@@ -81,6 +85,7 @@ public enum CalculatorEngine {
 			preferenceKeys.add(numeralBase.getKey());
 			preferenceKeys.add(angleUnit.getKey());
 			preferenceKeys.add(scienceNotation.getKey());
+			preferenceKeys.add(maxCalculationTime.getKey());
 		}
 
 		@NotNull
@@ -89,9 +94,6 @@ public enum CalculatorEngine {
 		}
 	}
 
-
-	public static final int DEFAULT_TIMEOUT = 3000;
-
 	@NotNull
 	private final Object lock = new Object();
 
@@ -115,8 +117,8 @@ public enum CalculatorEngine {
 	@NotNull
 	private ThreadKiller threadKiller = new AndroidThreadKiller();
 
-	// calculation thread timeout in milliseconds, after timeout thread would be interrupted
-	private int timeout = DEFAULT_TIMEOUT;
+	// calculation thread timeout in seconds, after timeout thread would be interrupted
+	private int timeout = Integer.valueOf(MAX_CALCULATION_TIME_DEFAULT);
 
 	@NotNull
 	private String multiplicationSign = MULTIPLICATION_SIGN_DEFAULT;
@@ -245,7 +247,7 @@ public enum CalculatorEngine {
 
 			try {
 				//Log.d(CalculatorEngine.class.getName(), "Main thread is waiting: " + Thread.currentThread().getName());
-				latch.await(timeout, TimeUnit.MILLISECONDS);
+				latch.await(timeout, TimeUnit.SECONDS);
 				//Log.d(CalculatorEngine.class.getName(), "Main thread got up: " + Thread.currentThread().getName());
 
 				final CalculatorParseException parseExceptionObject = parseException.getObject();
@@ -320,6 +322,7 @@ public enum CalculatorEngine {
 				this.setNumeralBase(getNumeralBaseFromPrefs(preferences));
 				this.setMultiplicationSign(Preferences.multiplicationSign.getPreference(preferences));
 				this.setScienceNotation(Preferences.scienceNotation.getPreference(preferences));
+				this.setTimeout(Preferences.maxCalculationTime.getPreference(preferences));
 
 				final String groupingSeparator = Preferences.groupingSeparator.getPreference(preferences);
 				if (StringUtils.isEmpty(groupingSeparator)) {
@@ -375,7 +378,7 @@ public enum CalculatorEngine {
 		return engine;
 	}
 
-	// for tests
+	// package protected for tests
 	void setTimeout(int timeout) {
 		this.timeout = timeout;
 	}