diff --git a/src/gguf_reader.hpp b/src/gguf_reader.hpp
index 2cc4d9d9c..9a2ceebcf 100644
--- a/src/gguf_reader.hpp
+++ b/src/gguf_reader.hpp
@@ -59,6 +59,9 @@ class GGUFReader {
         if (!safe_read(fin, key_len))
             return false;
 
+        if (key_len > 4096)
+            return false;
+
         std::string key(key_len, '\0');
         if (!safe_read(fin, (char*)key.data(), key_len))
             return false;
diff --git a/src/model.cpp b/src/model.cpp
index 1ccb03cf3..1639c161f 100644
--- a/src/model.cpp
+++ b/src/model.cpp
@@ -315,8 +315,9 @@ bool is_safetensors_file(const std::string& file_path) {
     if (!file) {
         return false;
     }
-    nlohmann::json header_ = nlohmann::json::parse(header_buf.data());
-    if (header_.is_discarded()) {
+    try {
+        nlohmann::json header_ = nlohmann::json::parse(header_buf.data());
+    } catch (const std::exception&) {
         return false;
     }
     return true;
@@ -511,7 +512,14 @@ bool ModelLoader::init_from_safetensors_file(const std::string& file_path, const
         return false;
     }
 
-    nlohmann::json header_ = nlohmann::json::parse(header_buf.data());
+    nlohmann::json header_;
+    try {
+        header_ = nlohmann::json::parse(header_buf.data());
+    } catch (const std::exception&) {
+        LOG_ERROR("parsing safetensors header failed", file_path.c_str());
+        file_paths_.pop_back();
+        return false;
+    }
 
     for (auto& item : header_.items()) {
         std::string name           = item.key();
@@ -575,24 +583,29 @@ bool ModelLoader::init_from_safetensors_file(const std::string& file_path, const
 
         size_t tensor_data_size = end - begin;
 
+        bool tensor_size_ok;
         if (dtype == "F8_E4M3") {
             tensor_storage.is_f8_e4m3 = true;
             // f8 -> f16
-            GGML_ASSERT(tensor_storage.nbytes() == tensor_data_size * 2);
+            tensor_size_ok = (tensor_storage.nbytes() == tensor_data_size * 2);
         } else if (dtype == "F8_E5M2") {
             tensor_storage.is_f8_e5m2 = true;
             // f8 -> f16
-            GGML_ASSERT(tensor_storage.nbytes() == tensor_data_size * 2);
+            tensor_size_ok = (tensor_storage.nbytes() == tensor_data_size * 2);
         } else if (dtype == "F64") {
             tensor_storage.is_f64 = true;
             // f64 -> f32
-            GGML_ASSERT(tensor_storage.nbytes() * 2 == tensor_data_size);
+            tensor_size_ok = (tensor_storage.nbytes() * 2 == tensor_data_size);
         } else if (dtype == "I64") {
             tensor_storage.is_i64 = true;
             // i64 -> i32
-            GGML_ASSERT(tensor_storage.nbytes() * 2 == tensor_data_size);
+            tensor_size_ok = (tensor_storage.nbytes() * 2 == tensor_data_size);
         } else {
-            GGML_ASSERT(tensor_storage.nbytes() == tensor_data_size);
+            tensor_size_ok = (tensor_storage.nbytes() == tensor_data_size);
+        }
+        if (!tensor_size_ok) {
+            LOG_ERROR("size mismatch for tensor '%s' (%s)\n", name.c_str(), dtype.c_str());
+            return false;
         }
 
         add_tensor_storage(tensor_storage);