diff --git a/src/NativeProviders/MKL/fft.cpp b/src/NativeProviders/MKL/fft.cpp
index b4603d71..a3598c89 100644
--- a/src/NativeProviders/MKL/fft.cpp
+++ b/src/NativeProviders/MKL/fft.cpp
@@ -7,11 +7,11 @@
 #include "mkl_dfti.h"
 
 template<typename Data, typename Precision, typename FFT>
-inline MKL_LONG fft_1d_inplace(const MKL_LONG n, Data x[], const Precision forward_scale, const Precision backward_scale, const DFTI_CONFIG_VALUE precision, const DFTI_CONFIG_VALUE domain, FFT fft)
+inline MKL_INT64 fft_1d_inplace(const MKL_INT64 n, Data x[], const Precision forward_scale, const Precision backward_scale, const DFTI_CONFIG_VALUE precision, const DFTI_CONFIG_VALUE domain, FFT fft)
 {
 	MKL_LONG status;
 	DFTI_DESCRIPTOR_HANDLE descriptor = nullptr;
-	status = DftiCreateDescriptor(&descriptor, precision, domain, 1, n);
+	status = DftiCreateDescriptor(&descriptor, precision, domain, 1, static_cast<MKL_LONG>(n));
 	if (0 != status) goto cleanup;
 
 	status = DftiSetValue(descriptor, DFTI_FORWARD_SCALE, forward_scale);
@@ -27,27 +27,27 @@ inline MKL_LONG fft_1d_inplace(const MKL_LONG n, Data x[], const Precision forwa
 
 cleanup:
 	DftiFreeDescriptor(&descriptor);
-	return status;
+	return static_cast<MKL_INT64>(status);
 }
 
 extern "C" {
 
-	DLLEXPORT MKL_LONG z_fft_forward_inplace(const MKL_LONG n, const double scaling, MKL_Complex16 x[])
+	DLLEXPORT MKL_INT64 z_fft_forward_inplace(const MKL_INT64 n, const double scaling, MKL_Complex16 x[])
 	{
 		return fft_1d_inplace(n, x, scaling, 1.0, DFTI_DOUBLE, DFTI_COMPLEX, DftiComputeForward);
 	}
 
-	DLLEXPORT MKL_LONG c_fft_forward_inplace(const MKL_LONG n, const float scaling, MKL_Complex8 x[])
+	DLLEXPORT MKL_INT64 c_fft_forward_inplace(const MKL_INT64 n, const float scaling, MKL_Complex8 x[])
 	{
 		return fft_1d_inplace(n, x, scaling, 1.0f, DFTI_SINGLE, DFTI_COMPLEX, DftiComputeForward);
 	}
 
-	DLLEXPORT MKL_LONG z_fft_backward_inplace(const MKL_LONG n, const double scaling, MKL_Complex16 x[])
+	DLLEXPORT MKL_INT64 z_fft_backward_inplace(const MKL_INT64 n, const double scaling, MKL_Complex16 x[])
 	{
 		return fft_1d_inplace(n, x, 1.0, scaling, DFTI_DOUBLE, DFTI_COMPLEX, DftiComputeBackward);
 	}
 
-	DLLEXPORT MKL_LONG c_fft_backward_inplace(const MKL_LONG n, const float scaling, MKL_Complex8 x[])
+	DLLEXPORT MKL_INT64 c_fft_backward_inplace(const MKL_INT64 n, const float scaling, MKL_Complex8 x[])
 	{
 		return fft_1d_inplace(n, x, 1.0f, scaling, DFTI_SINGLE, DFTI_COMPLEX, DftiComputeBackward);
 	}