diff --git a/model.cpp b/model.cpp
index 912e2e43..71b3c1bb 100644
--- a/model.cpp
+++ b/model.cpp
@@ -14,6 +14,8 @@
 #include "ggml/ggml-backend.h"
 #include "ggml/ggml.h"
 
+#define ST_HEADER_SIZE_LEN 8
+
 uint64_t read_u64(uint8_t* buffer) {
     // little endian
     uint64_t value = 0;
@@ -533,17 +535,89 @@ std::map<char, int> unicode_to_byte() {
     return byte_decoder;
 }
 
+bool is_zip_file(const std::string& file_path) {
+    struct zip_t* zip = zip_open(file_path.c_str(), 0, 'r');
+    if (zip == NULL) {
+        return false;
+    }
+    zip_close(zip);
+    return true;
+}
+
+bool is_gguf_file(const std::string& file_path) {
+    std::ifstream file(file_path, std::ios::binary);
+    if (!file.is_open()) {
+        return false;
+    }
+
+    char magic[4];
+
+    file.read(magic, sizeof(magic));
+    if (!file) {
+        return false;
+    }
+    for (uint32_t i = 0; i < sizeof(magic); i++) {
+        if (magic[i] != GGUF_MAGIC[i]) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+bool is_safetensors_file(const std::string& file_path) {
+    std::ifstream file(file_path, std::ios::binary);
+    if (!file.is_open()) {
+        return false;
+    }
+
+    // get file size
+    file.seekg(0, file.end);
+    size_t file_size_ = file.tellg();
+    file.seekg(0, file.beg);
+
+    // read header size
+    if (file_size_ <= ST_HEADER_SIZE_LEN) {
+        return false;
+    }
+
+    uint8_t header_size_buf[ST_HEADER_SIZE_LEN];
+    file.read((char*)header_size_buf, ST_HEADER_SIZE_LEN);
+    if (!file) {
+        return false;
+    }
+
+    size_t header_size_ = read_u64(header_size_buf);
+    if (header_size_ >= file_size_) {
+        return false;
+    }
+
+    // read header
+    std::vector<char> header_buf;
+    header_buf.resize(header_size_ + 1);
+    header_buf[header_size_] = '\0';
+    file.read(header_buf.data(), header_size_);
+    if (!file) {
+        return false;
+    }
+    nlohmann::json header_ = nlohmann::json::parse(header_buf.data());
+    if (header_.is_discarded()) {
+        return false;
+    }
+    return true;
+}
+
 bool ModelLoader::init_from_file(const std::string& file_path, const std::string& prefix) {
     if (is_directory(file_path)) {
         LOG_INFO("load %s using diffusers format", file_path.c_str());
         return init_from_diffusers_file(file_path, prefix);
-    } else if (ends_with(file_path, ".gguf")) {
+    } else if (is_gguf_file(file_path)) {
         LOG_INFO("load %s using gguf format", file_path.c_str());
         return init_from_gguf_file(file_path, prefix);
-    } else if (ends_with(file_path, ".safetensors")) {
+    } else if (is_safetensors_file(file_path)) {
         LOG_INFO("load %s using safetensors format", file_path.c_str());
         return init_from_safetensors_file(file_path, prefix);
-    } else if (ends_with(file_path, ".ckpt")) {
+    } else if (is_zip_file(file_path)) {
         LOG_INFO("load %s using checkpoint format", file_path.c_str());
         return init_from_ckpt_file(file_path, prefix);
     } else {
@@ -593,8 +667,6 @@ bool ModelLoader::init_from_gguf_file(const std::string& file_path, const std::s
 
 /*================================================= SafeTensorsModelLoader ==================================================*/
 
-#define ST_HEADER_SIZE_LEN 8
-
 ggml_type str_to_ggml_type(const std::string& dtype) {
     ggml_type ttype = GGML_TYPE_COUNT;
     if (dtype == "F16") {