diff --git a/dlls/imaadp32.acm/imaadp32.c b/dlls/imaadp32.acm/imaadp32.c
index 9518adc3450..a93b5f6af7c 100644
--- a/dlls/imaadp32.acm/imaadp32.c
+++ b/dlls/imaadp32.acm/imaadp32.c
@@ -530,13 +530,13 @@ static	LRESULT ADPCM_DriverDetails(PACMDRIVERDETAILSW add)
     add->cFilterTags = 0;
     add->hicon = NULL;
     MultiByteToWideChar( CP_ACP, 0, "Microsoft IMA ADPCM", -1,
-                         add->szShortName, sizeof(add->szShortName)/sizeof(WCHAR) );
+                         add->szShortName, ARRAY_SIZE(add->szShortName) );
     MultiByteToWideChar( CP_ACP, 0, "Microsoft IMA ADPCM CODEC", -1,
-                         add->szLongName, sizeof(add->szLongName)/sizeof(WCHAR) );
+                         add->szLongName, ARRAY_SIZE(add->szLongName) );
     MultiByteToWideChar( CP_ACP, 0, "Brought to you by the Wine team...", -1,
-                         add->szCopyright, sizeof(add->szCopyright)/sizeof(WCHAR) );
+                         add->szCopyright, ARRAY_SIZE(add->szCopyright) );
     MultiByteToWideChar( CP_ACP, 0, "Refer to LICENSE file", -1,
-                         add->szLicensing, sizeof(add->szLicensing)/sizeof(WCHAR) );
+                         add->szLicensing, ARRAY_SIZE(add->szLicensing) );
     add->szFeatures[0] = 0;
 
     return MMSYSERR_NOERROR;