diff --git a/native/jni/src/suggest/core/dictionary/binary_dictionary_format_utils.cpp b/native/jni/src/suggest/core/dictionary/binary_dictionary_format_utils.cpp
index f48386b..5d14a05 100644
--- a/native/jni/src/suggest/core/dictionary/binary_dictionary_format_utils.cpp
+++ b/native/jni/src/suggest/core/dictionary/binary_dictionary_format_utils.cpp
@@ -31,9 +31,9 @@
 // The versions of Latin IME that only handle format version 1 only test for the magic
 // number, so we had to change it so that version 2 files would be rejected by older
 // implementations. On this occasion, we made the magic number 32 bits long.
-const uint32_t BinaryDictionaryFormatUtils::FORMAT_VERSION_2_MAGIC_NUMBER = 0x9BC13AFE;
+const uint32_t BinaryDictionaryFormatUtils::HEADER_VERSION_2_MAGIC_NUMBER = 0x9BC13AFE;
 // Magic number (4 bytes), version (2 bytes), options (2 bytes), header size (4 bytes) = 12
-const int BinaryDictionaryFormatUtils::FORMAT_VERSION_2_MINIMUM_SIZE = 12;
+const int BinaryDictionaryFormatUtils::HEADER_VERSION_2_MINIMUM_SIZE = 12;
 
 /* static */ BinaryDictionaryFormatUtils::FORMAT_VERSION
         BinaryDictionaryFormatUtils::detectFormatVersion(const uint8_t *const dict,
@@ -46,25 +46,28 @@
     }
     const uint32_t magicNumber = ByteArrayUtils::readUint32(dict, 0);
     switch (magicNumber) {
-    case FORMAT_VERSION_2_MAGIC_NUMBER:
-        // Version 2 dictionaries are at least 12 bytes long.
-        // If this dictionary has the version 2 magic number but is less than 12 bytes long,
-        // then it's an unknown format and we need to avoid confidently reading the next bytes.
-        if (dictSize < FORMAT_VERSION_2_MINIMUM_SIZE) {
+        case HEADER_VERSION_2_MAGIC_NUMBER:
+            // Version 2 header are at least 12 bytes long.
+            // If this header has the version 2 magic number but is less than 12 bytes long,
+            // then it's an unknown format and we need to avoid confidently reading the next bytes.
+            if (dictSize < HEADER_VERSION_2_MINIMUM_SIZE) {
+                return UNKNOWN_VERSION;
+            }
+            // Version 2 header is as follows:
+            // Magic number (4 bytes) 0x9B 0xC1 0x3A 0xFE
+            // Version number (2 bytes)
+            // Options (2 bytes)
+            // Header size (4 bytes) : integer, big endian
+            if (ByteArrayUtils::readUint16(dict, 4) == 2) {
+                return VERSION_2;
+            } else if (ByteArrayUtils::readUint16(dict, 4) == 3) {
+                // TODO: Support version 3 dictionary.
+                return UNKNOWN_VERSION;
+            } else {
+                return UNKNOWN_VERSION;
+            }
+        default:
             return UNKNOWN_VERSION;
-        }
-        // Format 2 header is as follows:
-        // Magic number (4 bytes) 0x9B 0xC1 0x3A 0xFE
-        // Version number (2 bytes) 0x00 0x02
-        // Options (2 bytes)
-        // Header size (4 bytes) : integer, big endian
-        if (ByteArrayUtils::readUint16(dict, 4) == 2) {
-            return VERSION_2;
-        } else {
-            return UNKNOWN_VERSION;
-        }
-    default:
-        return UNKNOWN_VERSION;
     }
 }
 
diff --git a/native/jni/src/suggest/core/dictionary/binary_dictionary_format_utils.h b/native/jni/src/suggest/core/dictionary/binary_dictionary_format_utils.h
index 80067b2..830684c 100644
--- a/native/jni/src/suggest/core/dictionary/binary_dictionary_format_utils.h
+++ b/native/jni/src/suggest/core/dictionary/binary_dictionary_format_utils.h
@@ -33,9 +33,9 @@
  */
 class BinaryDictionaryFormatUtils {
  public:
-    // TODO: Support version 3 format.
     enum FORMAT_VERSION {
-        VERSION_2 = 1,
+        VERSION_2,
+        VERSION_3,
         UNKNOWN_VERSION
     };
 
@@ -45,8 +45,8 @@
     DISALLOW_IMPLICIT_CONSTRUCTORS(BinaryDictionaryFormatUtils);
 
     static const int DICTIONARY_MINIMUM_SIZE;
-    static const uint32_t FORMAT_VERSION_2_MAGIC_NUMBER;
-    static const int FORMAT_VERSION_2_MINIMUM_SIZE;
+    static const uint32_t HEADER_VERSION_2_MAGIC_NUMBER;
+    static const int HEADER_VERSION_2_MINIMUM_SIZE;
 };
 } // namespace latinime
 #endif /* LATINIME_BINARY_DICTIONARY_FORMAT_UTILS_H */
diff --git a/native/jni/src/suggest/core/dictionary/binary_dictionary_header_reading_utils.cpp b/native/jni/src/suggest/core/dictionary/binary_dictionary_header_reading_utils.cpp
index 6e1b15c..1e437dd 100644
--- a/native/jni/src/suggest/core/dictionary/binary_dictionary_header_reading_utils.cpp
+++ b/native/jni/src/suggest/core/dictionary/binary_dictionary_header_reading_utils.cpp
@@ -26,10 +26,10 @@
 
 const int BinaryDictionaryHeaderReadingUtils::MAX_OPTION_KEY_LENGTH = 256;
 
-const int BinaryDictionaryHeaderReadingUtils::VERSION_2_MAGIC_NUMBER_SIZE = 4;
-const int BinaryDictionaryHeaderReadingUtils::VERSION_2_DICTIONARY_VERSION_SIZE = 2;
-const int BinaryDictionaryHeaderReadingUtils::VERSION_2_DICTIONARY_FLAG_SIZE = 2;
-const int BinaryDictionaryHeaderReadingUtils::VERSION_2_DICTIONARY_HEADER_SIZE_SIZE = 4;
+const int BinaryDictionaryHeaderReadingUtils::VERSION_2_HEADER_MAGIC_NUMBER_SIZE = 4;
+const int BinaryDictionaryHeaderReadingUtils::VERSION_2_HEADER_DICTIONARY_VERSION_SIZE = 2;
+const int BinaryDictionaryHeaderReadingUtils::VERSION_2_HEADER_FLAG_SIZE = 2;
+const int BinaryDictionaryHeaderReadingUtils::VERSION_2_HEADER_SIZE_FIELD_SIZE = 4;
 
 const BinaryDictionaryHeaderReadingUtils::DictionaryFlags
         BinaryDictionaryHeaderReadingUtils::NO_FLAGS = 0;
@@ -45,13 +45,13 @@
 
 /* static */ int BinaryDictionaryHeaderReadingUtils::getHeaderSize(
         const BinaryDictionaryInfo *const binaryDictionaryInfo) {
-    switch (binaryDictionaryInfo->getFormat()) {
-        case BinaryDictionaryFormatUtils::VERSION_2:
+    switch (getHeaderVersion(binaryDictionaryInfo->getFormat())) {
+        case HEADER_VERSION_2:
             // See the format of the header in the comment in
             // BinaryDictionaryFormatUtils::detectFormatVersion()
             return ByteArrayUtils::readUint32(binaryDictionaryInfo->getDictBuf(),
-                    VERSION_2_MAGIC_NUMBER_SIZE + VERSION_2_DICTIONARY_VERSION_SIZE
-                            + VERSION_2_DICTIONARY_FLAG_SIZE);
+                    VERSION_2_HEADER_MAGIC_NUMBER_SIZE + VERSION_2_HEADER_DICTIONARY_VERSION_SIZE
+                            + VERSION_2_HEADER_FLAG_SIZE);
         default:
             return S_INT_MAX;
     }
@@ -60,10 +60,10 @@
 /* static */ BinaryDictionaryHeaderReadingUtils::DictionaryFlags
         BinaryDictionaryHeaderReadingUtils::getFlags(
                 const BinaryDictionaryInfo *const binaryDictionaryInfo) {
-    switch (binaryDictionaryInfo->getFormat()) {
-        case BinaryDictionaryFormatUtils::VERSION_2:
+    switch (getHeaderVersion(binaryDictionaryInfo->getFormat())) {
+        case HEADER_VERSION_2:
             return ByteArrayUtils::readUint16(binaryDictionaryInfo->getDictBuf(),
-                    VERSION_2_MAGIC_NUMBER_SIZE + VERSION_2_DICTIONARY_VERSION_SIZE);
+                    VERSION_2_HEADER_MAGIC_NUMBER_SIZE + VERSION_2_HEADER_DICTIONARY_VERSION_SIZE);
         default:
             return NO_FLAGS;
     }
@@ -73,11 +73,15 @@
 /* static */ bool BinaryDictionaryHeaderReadingUtils::readHeaderValue(
         const BinaryDictionaryInfo *const binaryDictionaryInfo,
         const char *const key, int *outValue, const int outValueSize) {
-    if (outValueSize <= 0 || !hasHeaderAttributes(binaryDictionaryInfo->getFormat())) {
+    if (outValueSize <= 0) {
         return false;
     }
     const int headerSize = getHeaderSize(binaryDictionaryInfo);
     int pos = getHeaderOptionsPosition(binaryDictionaryInfo->getFormat());
+    if (pos == NOT_A_DICT_POS) {
+        // The header doesn't have header options.
+        return false;
+    }
     while (pos < headerSize) {
         if(ByteArrayUtils::compareStringInBufferWithCharArray(
                 binaryDictionaryInfo->getDictBuf(), key, headerSize - pos, &pos) == 0) {
diff --git a/native/jni/src/suggest/core/dictionary/binary_dictionary_header_reading_utils.h b/native/jni/src/suggest/core/dictionary/binary_dictionary_header_reading_utils.h
index 94b9e12..6174822 100644
--- a/native/jni/src/suggest/core/dictionary/binary_dictionary_header_reading_utils.h
+++ b/native/jni/src/suggest/core/dictionary/binary_dictionary_header_reading_utils.h
@@ -48,27 +48,15 @@
         return (flags & FRENCH_LIGATURE_PROCESSING_FLAG) != 0;
     }
 
-    static AK_FORCE_INLINE bool hasHeaderAttributes(
-            const BinaryDictionaryFormatUtils::FORMAT_VERSION format) {
-        // Only format 2 and above have header attributes as {key,value} string pairs.
-        switch (format) {
-        case BinaryDictionaryFormatUtils::VERSION_2:
-            return  true;
-            break;
-        default:
-            return false;
-        }
-    }
-
     static AK_FORCE_INLINE int getHeaderOptionsPosition(
-            const BinaryDictionaryFormatUtils::FORMAT_VERSION format) {
-        switch (format) {
-        case BinaryDictionaryFormatUtils::VERSION_2:
-            return VERSION_2_MAGIC_NUMBER_SIZE + VERSION_2_DICTIONARY_VERSION_SIZE
-                    + VERSION_2_DICTIONARY_FLAG_SIZE + VERSION_2_DICTIONARY_HEADER_SIZE_SIZE;
+            const BinaryDictionaryFormatUtils::FORMAT_VERSION dictionaryFormat) {
+        switch (getHeaderVersion(dictionaryFormat)) {
+        case HEADER_VERSION_2:
+            return VERSION_2_HEADER_MAGIC_NUMBER_SIZE + VERSION_2_HEADER_DICTIONARY_VERSION_SIZE
+                    + VERSION_2_HEADER_FLAG_SIZE + VERSION_2_HEADER_SIZE_FIELD_SIZE;
             break;
         default:
-            return 0;
+            return NOT_A_DICT_POS;
         }
     }
 
@@ -82,10 +70,15 @@
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(BinaryDictionaryHeaderReadingUtils);
 
-    static const int VERSION_2_MAGIC_NUMBER_SIZE;
-    static const int VERSION_2_DICTIONARY_VERSION_SIZE;
-    static const int VERSION_2_DICTIONARY_FLAG_SIZE;
-    static const int VERSION_2_DICTIONARY_HEADER_SIZE_SIZE;
+    enum HEADER_VERSION {
+        HEADER_VERSION_2,
+        UNKNOWN_HEADER_VERSION
+    };
+
+    static const int VERSION_2_HEADER_MAGIC_NUMBER_SIZE;
+    static const int VERSION_2_HEADER_DICTIONARY_VERSION_SIZE;
+    static const int VERSION_2_HEADER_FLAG_SIZE;
+    static const int VERSION_2_HEADER_SIZE_FIELD_SIZE;
 
     static const DictionaryFlags NO_FLAGS;
     // Flags for special processing
@@ -95,6 +88,18 @@
     static const DictionaryFlags SUPPORTS_DYNAMIC_UPDATE_FLAG;
     static const DictionaryFlags FRENCH_LIGATURE_PROCESSING_FLAG;
     static const DictionaryFlags CONTAINS_BIGRAMS_FLAG;
+
+    static HEADER_VERSION getHeaderVersion(
+            const BinaryDictionaryFormatUtils::FORMAT_VERSION formatVersion) {
+        switch(formatVersion) {
+            case BinaryDictionaryFormatUtils::VERSION_2:
+                // Fall through
+            case BinaryDictionaryFormatUtils::VERSION_3:
+                return HEADER_VERSION_2;
+            default:
+                return UNKNOWN_HEADER_VERSION;
+        }
+    }
 };
 }
 #endif /* LATINIME_DICTIONARY_HEADER_READING_UTILS_H */
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_policy_factory.h b/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_policy_factory.h
index c0e24fa..70dad67 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_policy_factory.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_policy_factory.h
@@ -32,6 +32,9 @@
         switch (dictionaryFormat) {
             case BinaryDictionaryFormatUtils::VERSION_2:
                 return PatriciaTriePolicy::getInstance();
+            case BinaryDictionaryFormatUtils::VERSION_3:
+                // TODO: support version 3 dictionaries.
+                return 0;
             default:
                 ASSERT(false);
                 return 0;