diff --git a/dlls/msacm32/tests/msacm.c b/dlls/msacm32/tests/msacm.c
index 13494a6e96b..44a6febb662 100644
--- a/dlls/msacm32/tests/msacm.c
+++ b/dlls/msacm32/tests/msacm.c
@@ -1139,6 +1139,18 @@ static void test_acmFormatSuggest(void)
     ok(rc == MMSYSERR_INVALPARAM, "failed with error 0x%x\n", rc);
 }
 
+static void test_acmFormatTagDetails(void)
+{
+    ACMFORMATTAGDETAILSW aftd = {0};
+    MMRESULT rc;
+
+    aftd.cbStruct = sizeof(aftd);
+    aftd.dwFormatTag = WAVE_FORMAT_MPEGLAYER3;
+    rc = acmFormatTagDetailsW(NULL, &aftd, ACM_FORMATTAGDETAILSF_FORMATTAG);
+    if (rc == MMSYSERR_NOERROR)
+        ok(aftd.cbFormatSize == sizeof(MPEGLAYER3WAVEFORMAT), "got %d\n", aftd.cbFormatSize);
+}
+
 static struct
 {
     struct
@@ -1306,6 +1318,7 @@ START_TEST(msacm)
     driver_tests();
     test_prepareheader();
     test_acmFormatSuggest();
+    test_acmFormatTagDetails();
     /* Test acmDriverAdd in the end as it may conflict
      * with other tests due to codec lookup order */
     test_acmDriverAdd();
diff --git a/include/mmreg.h b/include/mmreg.h
index 2ee2b00aeb0..8bb581dd792 100644
--- a/include/mmreg.h
+++ b/include/mmreg.h
@@ -23,6 +23,8 @@
 #ifndef __WINE_MMREG_H
 #define __WINE_MMREG_H
 
+#include <pshpack1.h>
+
 /***********************************************************************
  * Defines/Enums
  */
@@ -512,6 +514,8 @@ typedef struct tagEXBMINFOHEADER {
 
 #endif
 
+#include <poppack.h>
+
 #endif /* __WINE_MMREG_H */
 
 #else /* __WIDL__ */