diff --git a/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java b/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
index 2dba713..cd18a6b 100644
--- a/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
+++ b/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
@@ -36,6 +36,7 @@
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Locale;
+import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CountDownLatch;
@@ -142,7 +143,8 @@
 
     @UsedForTesting
     public DictionaryFacilitatorForSuggest(final Context context, final Locale locale,
-            final ArrayList<String> dictionaryTypes, final HashMap<String, File> dictionaryFiles) {
+            final ArrayList<String> dictionaryTypes, final HashMap<String, File> dictionaryFiles,
+            final Map<String, Map<String, String>> additionalDictAttributes) {
         mContext = context;
         mLocale = locale;
         mLatchForWaitingLoadingMainDictionary = new CountDownLatch(0);
@@ -159,6 +161,10 @@
                 userHistoryDictionary.reloadDictionaryIfRequired();
                 userHistoryDictionary.waitAllTasksForTests();
                 setUserHistoryDictionary(userHistoryDictionary);
+                if (additionalDictAttributes.containsKey(dictType)) {
+                    userHistoryDictionary.clearAndFlushDictionaryWithAdditionalAttributes(
+                            additionalDictAttributes.get(dictType));
+                }
             } else if (dictType.equals(Dictionary.TYPE_PERSONALIZATION)) {
                 final PersonalizationDictionary personalizationDictionary =
                         PersonalizationHelper.getPersonalizationDictionary(context, locale);
@@ -167,6 +173,10 @@
                 personalizationDictionary.reloadDictionaryIfRequired();
                 personalizationDictionary.waitAllTasksForTests();
                 setPersonalizationDictionary(personalizationDictionary);
+                if (additionalDictAttributes.containsKey(dictType)) {
+                    personalizationDictionary.clearAndFlushDictionaryWithAdditionalAttributes(
+                            additionalDictAttributes.get(dictType));
+                }
             } else if (dictType.equals(Dictionary.TYPE_USER)) {
                 final File file = dictionaryFiles.get(dictType);
                 final UserBinaryDictionary userDictionary = new UserBinaryDictionary(
diff --git a/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java b/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
index d3734d6..8c358cd 100644
--- a/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
+++ b/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
@@ -50,6 +50,7 @@
     public final Locale mLocale;
 
     private final String mDictName;
+    private Map<String, String> mAdditionalAttributeMap = null;
 
     protected DecayingExpandableBinaryDictionaryBase(final Context context,
             final String dictName, final Locale locale, final String dictionaryType,
@@ -78,7 +79,10 @@
 
     @Override
     protected Map<String, String> getHeaderAttributeMap() {
-        HashMap<String, String> attributeMap = new HashMap<String, String>();
+        final Map<String, String> attributeMap = new HashMap<String, String>();
+        if (mAdditionalAttributeMap != null) {
+            attributeMap.putAll(mAdditionalAttributeMap);
+        }
         attributeMap.put(DictionaryHeader.USES_FORGETTING_CURVE_KEY,
                 DictionaryHeader.ATTRIBUTE_VALUE_TRUE);
         attributeMap.put(DictionaryHeader.HAS_HISTORICAL_INFO_KEY,
@@ -152,6 +156,13 @@
         asyncFlushBinaryDictionary();
     }
 
+    @UsedForTesting
+    public void clearAndFlushDictionaryWithAdditionalAttributes(
+            final Map<String, String> attributeMap) {
+        mAdditionalAttributeMap = attributeMap;
+        clearAndFlushDictionary();
+    }
+
     /* package */ void decayIfNeeded() {
         runGCIfRequired(false /* mindsBlockByGC */);
     }
diff --git a/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java b/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java
index a1d6415..562ff9e 100644
--- a/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java
+++ b/java/src/com/android/inputmethod/latin/utils/LanguageModelParam.java
@@ -37,9 +37,9 @@
     // non-0. Thus, it's not meaningful to compare 10, 100, and so on.
     // TODO: Revise the logic in ForgettingCurveUtils in native code.
     private static final int UNIGRAM_PROBABILITY_FOR_VALID_WORD = 100;
-    private static final int UNIGRAM_PROBABILITY_FOR_OOV_WORD = 10;
-    private static final int BIGRAM_PROBABILITY_FOR_VALID_WORD = 0;
-    private static final int BIGRAM_PROBABILITY_FOR_OOV_WORD = 0;
+    private static final int UNIGRAM_PROBABILITY_FOR_OOV_WORD = Dictionary.NOT_A_PROBABILITY;
+    private static final int BIGRAM_PROBABILITY_FOR_VALID_WORD = 10;
+    private static final int BIGRAM_PROBABILITY_FOR_OOV_WORD = Dictionary.NOT_A_PROBABILITY;
 
     public final String mTargetWord;
     public final int[] mWord0;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.cpp b/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.cpp
index 0bfebf3..a9baafe 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.cpp
@@ -30,6 +30,7 @@
 const int ForgettingCurveUtils::MAX_BIGRAM_COUNT = 12000;
 const int ForgettingCurveUtils::MAX_BIGRAM_COUNT_AFTER_GC = 10000;
 
+const int ForgettingCurveUtils::MULTIPLIER_TWO_IN_PROBABILITY_SCALE = 8;
 const int ForgettingCurveUtils::MAX_COMPUTED_PROBABILITY = 127;
 const int ForgettingCurveUtils::DECAY_INTERVAL_SECONDS = 2 * 60 * 60;
 
@@ -84,7 +85,9 @@
     } else if (bigramProbability == NOT_A_PROBABILITY) {
         return min(backoff(unigramProbability), MAX_COMPUTED_PROBABILITY);
     } else {
-        return min(max(unigramProbability, bigramProbability), MAX_COMPUTED_PROBABILITY);
+        // TODO: Investigate better way to handle bigram probability.
+        return min(max(unigramProbability, bigramProbability + MULTIPLIER_TWO_IN_PROBABILITY_SCALE),
+                MAX_COMPUTED_PROBABILITY);
     }
 }
 
@@ -137,11 +140,8 @@
 
 // See comments in ProbabilityUtils::backoff().
 /* static */ int ForgettingCurveUtils::backoff(const int unigramProbability) {
-    if (unigramProbability == NOT_A_PROBABILITY) {
-        return NOT_A_PROBABILITY;
-    } else {
-        return max(unigramProbability - 8, 0);
-    }
+    // See TODO comments in ForgettingCurveUtils::getProbability().
+    return unigramProbability;
 }
 
 /* static */ int ForgettingCurveUtils::getElapsedTimeStepCount(const int timestamp) {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h b/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h
index dae905e..1eb6fb7 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/forgetting_curve_utils.h
@@ -82,6 +82,7 @@
         static int getBaseProbabilityForLevel(const int tableId, const int level);
     };
 
+    static const int MULTIPLIER_TWO_IN_PROBABILITY_SCALE;
     static const int MAX_COMPUTED_PROBABILITY;
     static const int DECAY_INTERVAL_SECONDS;