diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.cpp
index f54bb15..0675de6 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.cpp
@@ -39,7 +39,7 @@
 }
 
 int LanguageModelDictContent::getWordProbability(const WordIdArrayView prevWordIds,
-        const int wordId) const {
+        const int wordId, const HeaderPolicy *const headerPolicy) const {
     int bitmapEntryIndices[MAX_PREV_WORD_COUNT_FOR_N_GRAM + 1];
     bitmapEntryIndices[0] = mTrieMap.getRootBitmapEntryIndex();
     int maxLevel = 0;
@@ -58,14 +58,15 @@
         if (!result.mIsValid) {
             continue;
         }
-        const int probability =
-                ProbabilityEntry::decode(result.mValue, mHasHistoricalInfo).getProbability();
+        const ProbabilityEntry probabilityEntry =
+                ProbabilityEntry::decode(result.mValue, mHasHistoricalInfo);
         if (mHasHistoricalInfo) {
-            return std::min(
-                    probability + ForgettingCurveUtils::getProbabilityBiasForNgram(i + 1 /* n */),
-                    MAX_PROBABILITY);
+            const int probability = ForgettingCurveUtils::decodeProbability(
+                    probabilityEntry.getHistoricalInfo(), headerPolicy)
+                            + ForgettingCurveUtils::getProbabilityBiasForNgram(i + 1 /* n */);
+            return std::min(probability, MAX_PROBABILITY);
         } else {
-            return probability;
+            return probabilityEntry.getProbability();
         }
     }
     // Cannot find the word.
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.h
index 4e0b470..a793af4 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content.h
@@ -128,7 +128,8 @@
             const LanguageModelDictContent *const originalContent,
             int *const outNgramCount);
 
-    int getWordProbability(const WordIdArrayView prevWordIds, const int wordId) const;
+    int getWordProbability(const WordIdArrayView prevWordIds, const int wordId,
+            const HeaderPolicy *const headerPolicy) const;
 
     ProbabilityEntry getProbabilityEntry(const int wordId) const {
         return getNgramProbabilityEntry(WordIdArrayView(), wordId);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
index e624bf3..1336a62 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
@@ -121,9 +121,10 @@
             mBuffers->getTerminalPositionLookupTable()->getTerminalPtNodePosition(wordId);
     const PtNodeParams ptNodeParams = mNodeReader.fetchPtNodeParamsInBufferFromPtNodePos(ptNodePos);
     // TODO: Support n-gram.
-    return WordAttributes(mBuffers->getLanguageModelDictContent()->getWordProbability(
-            prevWordIds.limit(1 /* maxSize */), wordId), ptNodeParams.isBlacklisted(),
-            ptNodeParams.isNotAWord(), ptNodeParams.getProbability() == 0);
+    const int probability = mBuffers->getLanguageModelDictContent()->getWordProbability(
+            prevWordIds.limit(1 /* maxSize */), wordId, mHeaderPolicy);
+    return WordAttributes(probability, ptNodeParams.isBlacklisted(), ptNodeParams.isNotAWord(),
+            probability == 0);
 }
 
 int Ver4PatriciaTriePolicy::getProbabilityOfWord(const WordIdArrayView prevWordIds,
diff --git a/native/jni/tests/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content_test.cpp b/native/jni/tests/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content_test.cpp
index 7608b45..c5849d0 100644
--- a/native/jni/tests/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content_test.cpp
+++ b/native/jni/tests/suggest/policyimpl/dictionary/structure/v4/content/language_model_dict_content_test.cpp
@@ -107,13 +107,15 @@
     languageModelDictContent.setProbabilityEntry(prevWordIds[0], &probabilityEntry);
     languageModelDictContent.setNgramProbabilityEntry(prevWordIds.limit(1), wordId,
             &bigramProbabilityEntry);
-    EXPECT_EQ(bigramProbability, languageModelDictContent.getWordProbability(prevWordIds, wordId));
+    EXPECT_EQ(bigramProbability, languageModelDictContent.getWordProbability(prevWordIds, wordId,
+            nullptr /* headerPolicy */));
     const ProbabilityEntry trigramProbabilityEntry(flag, trigramProbability);
     languageModelDictContent.setNgramProbabilityEntry(prevWordIds.limit(1),
             prevWordIds[1], &probabilityEntry);
     languageModelDictContent.setNgramProbabilityEntry(prevWordIds.limit(2), wordId,
             &trigramProbabilityEntry);
-    EXPECT_EQ(trigramProbability, languageModelDictContent.getWordProbability(prevWordIds, wordId));
+    EXPECT_EQ(trigramProbability, languageModelDictContent.getWordProbability(prevWordIds, wordId,
+            nullptr /* headerPolicy */));
 }
 
 }  // namespace