diff --git a/reactos/dll/3rdparty/dxtn/dxtn.def b/reactos/dll/3rdparty/dxtn/dxtn.def
deleted file mode 100644
index a8ca33887d9..00000000000
--- a/reactos/dll/3rdparty/dxtn/dxtn.def
+++ /dev/null
@@ -1,16 +0,0 @@
-LIBRARY dxtn
-EXPORTS
-dxt1_rgb_encode@28
-dxt1_rgba_encode@28
-dxt3_rgba_encode@28
-dxt5_rgba_encode@28
-dxt1_rgba_decode_1@20
-dxt3_rgba_decode_1@20
-dxt5_rgba_decode_1@20
-fxt1_encode@28
-fxt1_decode_1@20
-fetch_2d_texel_rgb_dxt1@20
-fetch_2d_texel_rgba_dxt1@20
-fetch_2d_texel_rgba_dxt3@20
-fetch_2d_texel_rgba_dxt5@20
-tx_compress_dxtn@28
diff --git a/reactos/dll/3rdparty/dxtn/dxtn.rbuild b/reactos/dll/3rdparty/dxtn/dxtn.rbuild
index f4e8d8815ef..dd49edcfafe 100644
--- a/reactos/dll/3rdparty/dxtn/dxtn.rbuild
+++ b/reactos/dll/3rdparty/dxtn/dxtn.rbuild
@@ -1,5 +1,5 @@
 <module name="dxtn" type="win32dll" entrypoint="0" installbase="system32" installname="dxtn.dll" allowwarnings="true" crt="msvcrt">
-	<importlibrary definition="dxtn.def" />
+	<importlibrary definition="dxtn.spec" />
 	<include base="dxtn">.</include>
 	<define name="__USE_W32API" />
 	<file>fxt1.c</file>
diff --git a/reactos/dll/3rdparty/dxtn/dxtn.spec b/reactos/dll/3rdparty/dxtn/dxtn.spec
new file mode 100644
index 00000000000..103f96916e2
--- /dev/null
+++ b/reactos/dll/3rdparty/dxtn/dxtn.spec
@@ -0,0 +1,14 @@
+@ stdcall dxt1_rgb_encode(long long long ptr long ptr long)
+@ stdcall dxt1_rgba_encode(long long long ptr long ptr long)
+@ stdcall dxt3_rgba_encode(long long long ptr long ptr long)
+@ stdcall dxt5_rgba_encode(long long long ptr long ptr long)
+@ stdcall dxt1_rgba_decode_1(ptr long long long long)
+@ stdcall dxt3_rgba_decode_1(ptr long long long long)
+@ stdcall dxt5_rgba_decode_1(ptr long long long long)
+@ stdcall fxt1_encode(long long long ptr long ptr long)
+@ stdcall fxt1_decode_1(ptr long long long long)
+@ stdcall fetch_2d_texel_rgb_dxt1(long ptr long long long)
+@ stdcall fetch_2d_texel_rgba_dxt1(long ptr long long long)
+@ stdcall fetch_2d_texel_rgba_dxt3(long ptr long long long)
+@ stdcall fetch_2d_texel_rgba_dxt5(long ptr long long long)
+@ stdcall tx_compress_dxtn(long long long ptr long ptr long)