diff --git a/dlls/mfplat/buffer.c b/dlls/mfplat/buffer.c
index e3f863c6345..18c77c87ec2 100644
--- a/dlls/mfplat/buffer.c
+++ b/dlls/mfplat/buffer.c
@@ -1264,7 +1264,8 @@ static HRESULT memory_buffer_init(struct buffer *buffer, DWORD max_length, DWORD
 {
     size_t size;
 
-    if (!alignment) alignment = MF_64_BYTE_ALIGNMENT;
+    if (alignment < MF_16_BYTE_ALIGNMENT)
+        alignment = MF_16_BYTE_ALIGNMENT;
     alignment++;
 
     if (alignment & (alignment - 1))