diff --git a/Azaion.Inference/inference.pyx b/Azaion.Inference/inference.pyx
index 48925de..d505e60 100644
--- a/Azaion.Inference/inference.pyx
+++ b/Azaion.Inference/inference.pyx
@@ -16,7 +16,7 @@ from hardware_service cimport HardwareService
 from security cimport Security
 
 if HardwareService.has_nvidia_gpu():
-    from tensorrt_engine import TensorRTEngine
+    from tensorrt_engine cimport TensorRTEngine
 else:
     from onnx_engine import OnnxEngine
 
diff --git a/Azaion.Inference/onnx_engine.pyx b/Azaion.Inference/onnx_engine.pyx
index de68d73..ed8cdeb 100644
--- a/Azaion.Inference/onnx_engine.pyx
+++ b/Azaion.Inference/onnx_engine.pyx
@@ -14,11 +14,11 @@ cdef class OnnxEngine(InferenceEngine):
         model_meta = self.session.get_modelmeta()
         print("Metadata:", model_meta.custom_metadata_map)
 
-    cpdef tuple get_input_shape(self):
+    cdef tuple get_input_shape(self):
         shape = self.input_shape
         return shape[2], shape[3]
 
-    cpdef int get_batch_size(self):
+    cdef int get_batch_size(self):
         return self.batch_size
 
     cpdef run(self, input_data):
diff --git a/Azaion.Inference/tensorrt_engine.pxd b/Azaion.Inference/tensorrt_engine.pxd
index 6fc31bd..90d8b79 100644
--- a/Azaion.Inference/tensorrt_engine.pxd
+++ b/Azaion.Inference/tensorrt_engine.pxd
@@ -16,9 +16,17 @@ cdef class TensorRTEngine(InferenceEngine):
 
     cdef object stream
 
+    @staticmethod
+    cdef get_gpu_memory_bytes(int device_id)
 
-    cpdef tuple get_input_shape(self)
+    @staticmethod
+    cdef get_engine_filename(int device_id)
 
-    cpdef int get_batch_size(self)
+    @staticmethod
+    cdef convert_from_onnx(bytes onnx_model)
 
-    cpdef run(self, input_data)
+    cdef tuple get_input_shape(self)
+
+    cdef int get_batch_size(self)
+
+    cdef run(self, input_data)
diff --git a/Azaion.Inference/tensorrt_engine.pyx b/Azaion.Inference/tensorrt_engine.pyx
index d8c4189..c7cf1a5 100644
--- a/Azaion.Inference/tensorrt_engine.pyx
+++ b/Azaion.Inference/tensorrt_engine.pyx
@@ -56,7 +56,7 @@ cdef class TensorRTEngine(InferenceEngine):
             raise RuntimeError(f"Failed to initialize TensorRT engine: {str(e)}")
 
     @staticmethod
-    def get_gpu_memory_bytes(int device_id):
+    cdef get_gpu_memory_bytes(int device_id):
         total_memory = None
         try:
             pynvml.nvmlInit()
@@ -73,7 +73,7 @@ cdef class TensorRTEngine(InferenceEngine):
         return 2 * 1024 * 1024 * 1024 if total_memory is None else total_memory # default 2 Gb
 
     @staticmethod
-    def get_engine_filename(int device_id):
+    cdef get_engine_filename(int device_id):
         try:
             device = cuda.Device(device_id)
             sm_count = device.multiprocessor_count
@@ -83,7 +83,7 @@ cdef class TensorRTEngine(InferenceEngine):
             return None
 
     @staticmethod
-    def convert_from_onnx(bytes onnx_model):
+    cdef convert_from_onnx(bytes onnx_model):
         workspace_bytes = int(TensorRTEngine.get_gpu_memory_bytes(0) * 0.9)
 
         explicit_batch_flag = 1 << int(trt.NetworkDefinitionCreationFlag.EXPLICIT_BATCH)
@@ -112,13 +112,13 @@ cdef class TensorRTEngine(InferenceEngine):
             constants.log('conversion done!')
             return bytes(plan)
 
-    cpdef tuple get_input_shape(self):
+    cdef tuple get_input_shape(self):
         return self.input_shape[2], self.input_shape[3]
 
-    cpdef int get_batch_size(self):
+    cdef int get_batch_size(self):
         return self.batch_size
 
-    cpdef run(self, input_data):
+    cdef run(self, input_data):
         try:
             cuda.memcpy_htod_async(self.d_input, input_data, self.stream)
             self.context.set_tensor_address(self.input_name, int(self.d_input))  # input buffer