diff --git a/configure b/configure
index 5f33c044ecd..ec15a909834 100755
--- a/configure
+++ b/configure
@@ -18805,6 +18805,7 @@ wine_fn_config_makefile dlls/monodebg.vxd enable_win16
 wine_fn_config_makefile dlls/mountmgr.sys enable_mountmgr_sys
 wine_fn_config_makefile dlls/mouse.drv16 enable_win16
 wine_fn_config_makefile dlls/mp3dmod enable_mp3dmod
+wine_fn_config_makefile dlls/mp3dmod/tests enable_tests
 wine_fn_config_makefile dlls/mpr enable_mpr
 wine_fn_config_makefile dlls/mpr/tests enable_tests
 wine_fn_config_makefile dlls/mprapi enable_mprapi
diff --git a/configure.ac b/configure.ac
index 5d60559ff66..312c235bb1d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3401,6 +3401,7 @@ WINE_CONFIG_MAKEFILE(dlls/monodebg.vxd,enable_win16)
 WINE_CONFIG_MAKEFILE(dlls/mountmgr.sys)
 WINE_CONFIG_MAKEFILE(dlls/mouse.drv16,enable_win16)
 WINE_CONFIG_MAKEFILE(dlls/mp3dmod)
+WINE_CONFIG_MAKEFILE(dlls/mp3dmod/tests)
 WINE_CONFIG_MAKEFILE(dlls/mpr)
 WINE_CONFIG_MAKEFILE(dlls/mpr/tests)
 WINE_CONFIG_MAKEFILE(dlls/mprapi)
diff --git a/dlls/mp3dmod/tests/Makefile.in b/dlls/mp3dmod/tests/Makefile.in
new file mode 100644
index 00000000000..3cbe4feb018
--- /dev/null
+++ b/dlls/mp3dmod/tests/Makefile.in
@@ -0,0 +1,5 @@
+TESTDLL = mp3dmod.dll
+IMPORTS = dmoguids ole32 strmiids uuid wmcodecdspuuid
+
+C_SRCS = \
+	mp3dmod.c
diff --git a/dlls/mp3dmod/tests/mp3dmod.c b/dlls/mp3dmod/tests/mp3dmod.c
new file mode 100644
index 00000000000..e1c5f2bc9f7
--- /dev/null
+++ b/dlls/mp3dmod/tests/mp3dmod.c
@@ -0,0 +1,233 @@
+/*
+ * Copyright 2018 Zebediah Figura
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+#define COBJMACROS
+#include "windef.h"
+#include "wingdi.h"
+#include "mmreg.h"
+#include "mmsystem.h"
+#include "mediaerr.h"
+#include "wmcodecdsp.h"
+#include "uuids.h"
+#include "wine/test.h"
+
+#include "initguid.h"
+DEFINE_GUID(WMMEDIASUBTYPE_MP3, 0x00000055, 0x0000, 0x0010, 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71);
+
+/* shorter aliases for flags */
+#define O_SYNCPOINT  DMO_OUTPUT_DATA_BUFFERF_SYNCPOINT
+#define O_TIME       DMO_OUTPUT_DATA_BUFFERF_TIME
+#define O_TIMELENGTH DMO_OUTPUT_DATA_BUFFERF_TIMELENGTH
+#define O_INCOMPLETE DMO_OUTPUT_DATA_BUFFERF_INCOMPLETE
+
+struct test_buffer {
+    IMediaBuffer IMediaBuffer_iface;
+    BYTE data[5000];
+    DWORD len;
+    DWORD maxlen;
+};
+
+static inline struct test_buffer *impl_from_IMediaBuffer(IMediaBuffer *iface)
+{
+    return CONTAINING_RECORD(iface, struct test_buffer, IMediaBuffer_iface);
+}
+
+static HRESULT WINAPI Buffer_QueryInterface(IMediaBuffer *iface, REFIID iid, void **obj)
+{
+    if (IsEqualIID(iid, &IID_IMediaBuffer) || IsEqualIID(iid, &IID_IUnknown))
+    {
+        *obj = iface;
+        return S_OK;
+    }
+    ok(0, "Unexpected IID %s\n", wine_dbgstr_guid(iid));
+    return E_NOINTERFACE;
+}
+
+static ULONG WINAPI Buffer_AddRef(IMediaBuffer *iface)
+{
+    return 2;
+}
+
+static ULONG WINAPI Buffer_Release(IMediaBuffer *iface)
+{
+    return 1;
+}
+
+static HRESULT WINAPI Buffer_SetLength(IMediaBuffer *iface, DWORD len)
+{
+    struct test_buffer *This = impl_from_IMediaBuffer(iface);
+    This->len = len;
+    return S_OK;
+}
+
+static HRESULT WINAPI Buffer_GetMaxLength(IMediaBuffer *iface, DWORD *len)
+{
+    struct test_buffer *This = impl_from_IMediaBuffer(iface);
+    *len = This->maxlen;
+    return S_OK;
+}
+
+static HRESULT WINAPI Buffer_GetBufferAndLength(IMediaBuffer *iface, BYTE **buf, DWORD *len)
+{
+    struct test_buffer *This = impl_from_IMediaBuffer(iface);
+    if (buf) *buf = This->data;
+    if (len) *len = This->len;
+    return S_OK;
+}
+
+static IMediaBufferVtbl Buffer_vtbl = {
+    Buffer_QueryInterface,
+    Buffer_AddRef,
+    Buffer_Release,
+    Buffer_SetLength,
+    Buffer_GetMaxLength,
+    Buffer_GetBufferAndLength,
+};
+
+static void test_convert(void)
+{
+    static const BYTE mp3hdr[] = {0xff,0xfb,0x14,0xc4};
+    struct test_buffer outbuf = {{&Buffer_vtbl}};
+    struct test_buffer inbuf = {{&Buffer_vtbl}};
+    DMO_MEDIA_TYPE in = {{0}}, out = {{0}};
+    MPEGLAYER3WAVEFORMAT mp3fmt = {{0}};
+    DMO_OUTPUT_DATA_BUFFER output;
+    WAVEFORMATEX wavfmt = {0};
+    IMediaObject *dmo;
+    DWORD written;
+    DWORD status;
+    HRESULT hr;
+    int i;
+
+    hr = CoCreateInstance(&CLSID_CMP3DecMediaObject, NULL, CLSCTX_INPROC_SERVER,
+        &IID_IMediaObject, (void **)&dmo);
+    ok(hr == S_OK, "got %#x\n", hr);
+
+    mp3fmt.wfx.wFormatTag = WAVE_FORMAT_MPEGLAYER3;
+    mp3fmt.wfx.nChannels = 2;
+    mp3fmt.wfx.nSamplesPerSec = 48000;
+    in.majortype = MEDIATYPE_Audio;
+    in.subtype = WMMEDIASUBTYPE_MP3;
+    in.formattype = FORMAT_WaveFormatEx;
+    in.cbFormat = sizeof(mp3fmt);
+    in.pbFormat = (BYTE *)&mp3fmt;
+
+    hr = IMediaObject_SetInputType(dmo, 0, &in, 0);
+    ok(hr == S_OK, "got %#x\n", hr);
+
+    wavfmt.wFormatTag = WAVE_FORMAT_PCM;
+    wavfmt.nChannels = 1;
+    wavfmt.nSamplesPerSec = 48000;
+    wavfmt.nAvgBytesPerSec = 48000 * ((1 * 8) / 8);
+    wavfmt.nBlockAlign = (1 * 8) / 8;
+    wavfmt.wBitsPerSample = 8;
+    out.majortype = MEDIATYPE_Audio;
+    out.subtype = MEDIASUBTYPE_PCM;
+    out.formattype = FORMAT_WaveFormatEx;
+    out.cbFormat = sizeof(wavfmt);
+    out.pbFormat = (BYTE *)&wavfmt;
+
+    hr = IMediaObject_SetOutputType(dmo, 0, &out, 0);
+    ok(hr == S_OK, "got %#x\n", hr);
+
+    outbuf.len = 0;
+    outbuf.maxlen = sizeof(outbuf.data);
+    output.pBuffer = &outbuf.IMediaBuffer_iface;
+    output.dwStatus = 0xdeadbeef;
+    hr = IMediaObject_ProcessOutput(dmo, 0, 1, &output, &status);
+    ok(hr == S_FALSE, "got %#x\n", hr);
+    ok(outbuf.len == 0, "got %u\n", outbuf.len);
+    ok(output.dwStatus == 0, "got %#x\n", output.dwStatus);
+
+    /* write several frames of mp3 data */
+    for (i = 0; i < 5; i++)
+        memcpy(inbuf.data + 96 * i, mp3hdr, 4);
+    inbuf.len = 96 * 5;
+    hr = IMediaObject_ProcessInput(dmo, 0, &inbuf.IMediaBuffer_iface, 0, 0, 0);
+    ok(hr == S_OK, "got %#x\n", hr);
+
+    hr = IMediaObject_ProcessInput(dmo, 0, &inbuf.IMediaBuffer_iface, 0, 0, 0);
+    ok(hr == DMO_E_NOTACCEPTING, "got %#x\n", hr);
+
+    outbuf.len = 0;
+    outbuf.maxlen = 0;
+    hr = IMediaObject_ProcessOutput(dmo, 0, 1, &output, &status);
+    ok(hr == S_FALSE, "got %#x\n", hr);
+    ok(outbuf.len == 0, "got %u\n", outbuf.len);
+    ok(output.dwStatus == (O_SYNCPOINT | O_INCOMPLETE), "got %#x\n", output.dwStatus);
+
+    /* implementations are inconsistent, but should write at least one frame of data */
+    outbuf.len = 0;
+    outbuf.maxlen = 5000;
+    hr = IMediaObject_ProcessOutput(dmo, 0, 1, &output, &status);
+    ok(hr == S_OK, "got %#x\n", hr);
+    written = outbuf.len;
+    ok(written > 1152 && written <= 5000, "got %u\n", written);
+todo_wine
+    ok(output.dwStatus == (O_SYNCPOINT | O_TIME | O_TIMELENGTH | O_INCOMPLETE),
+        "got %#x\n", output.dwStatus);
+
+    hr = IMediaObject_ProcessOutput(dmo, 0, 1, &output, &status);
+    ok(hr == S_FALSE, "got %#x\n", hr);
+    ok(outbuf.len == written, "expected %u, got %u\n", written, outbuf.len);
+    ok(output.dwStatus == (O_SYNCPOINT | O_INCOMPLETE), "got %#x\n", output.dwStatus);
+
+    hr = IMediaObject_ProcessInput(dmo, 0, &inbuf.IMediaBuffer_iface, 0, 0, 0);
+    ok(hr == DMO_E_NOTACCEPTING, "got %#x\n", hr);
+
+    /* write the rest */
+    outbuf.len = 0;
+    outbuf.maxlen = 5000;
+    hr = IMediaObject_ProcessOutput(dmo, 0, 1, &output, &status);
+    ok(hr == S_OK, "got %#x\n", hr);
+    ok(written + outbuf.len == (1152 * 5) ||
+        broken(written + outbuf.len == (1152 * 5) - 528), /* Win10 */
+        "got %u, total %u\n", outbuf.len, written + outbuf.len);
+todo_wine
+    ok(output.dwStatus == (O_SYNCPOINT | O_TIME | O_TIMELENGTH), "got %#x\n", output.dwStatus);
+
+    hr = IMediaObject_ProcessOutput(dmo, 0, 1, &output, &status);
+    ok(hr == S_FALSE, "got %#x\n", hr);
+    ok(output.dwStatus == 0, "got %#x\n", output.dwStatus);
+
+    hr = IMediaObject_ProcessInput(dmo, 0, &inbuf.IMediaBuffer_iface, 0, 0, 0);
+    ok(hr == S_OK, "got %#x\n", hr);
+
+    IMediaObject_Release(dmo);
+}
+
+START_TEST(mp3dmod)
+{
+    IMediaObject *dmo;
+    HRESULT hr;
+
+    CoInitializeEx(NULL, COINIT_MULTITHREADED);
+
+    hr = CoCreateInstance(&CLSID_CMP3DecMediaObject, NULL, CLSCTX_INPROC_SERVER,
+        &IID_IMediaObject, (void **)&dmo);
+    if (hr == REGDB_E_CLASSNOTREG)
+    {
+        win_skip("CLSID_CMP3DecMediaObject not available\n");
+        return;
+    }
+    IMediaObject_Release(dmo);
+
+    test_convert();
+
+    CoUninitialize();
+}