diff --git a/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.cpp
index bc2f5ee..29307b5 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.cpp
@@ -325,7 +325,7 @@
         nodeReader.fetchNodeInfoInBufferFromPtNodePos(currentPos);
         bigramLinkCount++;
         if (bigramLinkCount > CONTINUING_BIGRAM_LINK_COUNT_LIMIT) {
-            AKLOGE("Bigram link is invalid. start position: %d", bigramPos);
+            AKLOGE("Bigram link is invalid. start position: %d", originalBigramPos);
             ASSERT(false);
             return NOT_A_DICT_POS;
         }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h
index b033eee..c6d8ddc 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h
@@ -263,7 +263,7 @@
 
     AK_FORCE_INLINE void pushReadingStateToStack() {
         if (mReadingStateStack.size() > MAX_READING_STATE_STACK_SIZE) {
-            AKLOGI("Reading state stack overflow. Max size: %d", MAX_READING_STATE_STACK_SIZE);
+            AKLOGI("Reading state stack overflow. Max size: %zd", MAX_READING_STATE_STACK_SIZE);
             ASSERT(false);
             mIsError = true;
             mReadingState.mPos = NOT_A_DICT_POS;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp
index 5269795..8a84bd2 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.cpp
@@ -31,9 +31,21 @@
         return;
     }
     int nextPos = dicNode->getChildrenPos();
+    if (nextPos < 0 || nextPos >= mDictBufferSize) {
+        AKLOGE("Children PtNode array position is invalid. pos: %d, dict size: %d",
+                nextPos, mDictBufferSize);
+        ASSERT(false);
+        return;
+    }
     const int childCount = PatriciaTrieReadingUtils::getPtNodeArraySizeAndAdvancePosition(
             mDictRoot, &nextPos);
     for (int i = 0; i < childCount; i++) {
+        if (nextPos < 0 || nextPos >= mDictBufferSize) {
+            AKLOGE("Child PtNode position is invalid. pos: %d, dict size: %d, childCount: %d / %d",
+                    nextPos, mDictBufferSize, i, childCount);
+            ASSERT(false);
+            return;
+        }
         nextPos = createAndGetLeavingChildNode(dicNode, nextPos, childDicNodes);
     }
 }
@@ -404,6 +416,11 @@
     if (PatriciaTrieReadingUtils::hasBigrams(flags)) {
         getBigramsStructurePolicy()->skipAllBigrams(&pos);
     }
+    if (mergedNodeCodePointCount <= 0) {
+        AKLOGE("Empty PtNode is not allowed. Code point count: %d", mergedNodeCodePointCount);
+        ASSERT(false);
+        return pos;
+    }
     childDicNodes->pushLeavingChild(dicNode, ptNodePos, childrenPos, probability,
             PatriciaTrieReadingUtils::isTerminal(flags),
             PatriciaTrieReadingUtils::hasChildrenInFlags(flags),
diff --git a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
index 19155f9..f1de914 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
@@ -36,6 +36,7 @@
     PatriciaTriePolicy(const MmappedBuffer *const buffer)
             : mBuffer(buffer), mHeaderPolicy(mBuffer->getBuffer(), buffer->getBufferSize()),
               mDictRoot(mBuffer->getBuffer() + mHeaderPolicy.getSize()),
+              mDictBufferSize(mBuffer->getBufferSize() - mHeaderPolicy.getSize()),
               mBigramListPolicy(mDictRoot), mShortcutListPolicy(mDictRoot) {}
 
     ~PatriciaTriePolicy() {
@@ -118,6 +119,7 @@
     const MmappedBuffer *const mBuffer;
     const HeaderPolicy mHeaderPolicy;
     const uint8_t *const mDictRoot;
+    const int mDictBufferSize;
     const BigramListPolicy mBigramListPolicy;
     const ShortcutListPolicy mShortcutListPolicy;
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_reading_utils.cpp b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_reading_utils.cpp
index 1316b42..7df5581 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_reading_utils.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_reading_utils.cpp
@@ -71,8 +71,17 @@
         length = ByteArrayUtils::readStringAndAdvancePosition(buffer, maxLength, outBuffer,
                 pos);
     } else {
-        if (maxLength > 0) {
-            outBuffer[0] = getCodePointAndAdvancePosition(buffer, pos);
+        const int codePoint = getCodePointAndAdvancePosition(buffer, pos);
+        if (codePoint == NOT_A_CODE_POINT) {
+            // CAVEAT: codePoint == NOT_A_CODE_POINT means the code point is
+            // CHARACTER_ARRAY_TERMINATOR. The code point must not be CHARACTER_ARRAY_TERMINATOR
+            // when the PtNode has a single code point.
+            length = 0;
+            AKLOGE("codePoint is NOT_A_CODE_POINT. pos: %d, codePoint: 0x%x, buffer[pos - 1]: 0x%x",
+                    *pos - 1, codePoint, buffer[*pos - 1]);
+            ASSERT(false);
+        } else if (maxLength > 0) {
+            outBuffer[0] = codePoint;
             length = 1;
         }
     }