diff --git a/dlls/dsound/sound3d.c b/dlls/dsound/sound3d.c
index cae1c2804749f5ce90b8d44fb76b663d42d54499..4a26947f26f2bb61f0fa8f8e796b1489e61d0cef 100644
--- a/dlls/dsound/sound3d.c
+++ b/dlls/dsound/sound3d.c
@@ -238,6 +238,9 @@ void DSOUND_Calc3DBuffer(IDirectSoundBufferImpl *dsb)
 			/* my test show that for my way of calc., we need only half of angles */
 			DWORD dwInsideConeAngle = dsb->ds3db_ds3db.dwInsideConeAngle/2;
 			DWORD dwOutsideConeAngle = dsb->ds3db_ds3db.dwOutsideConeAngle/2;
+			if (dwOutsideConeAngle == dwInsideConeAngle)
+				++dwOutsideConeAngle;
+
 			/* full volume */
 			if (flAngle < dwInsideConeAngle)
 				flAngle = dwInsideConeAngle;