diff --git a/dll/ntdll/csr/capture.c b/dll/ntdll/csr/capture.c
index d22644b5992..0a779eca9f9 100644
--- a/dll/ntdll/csr/capture.c
+++ b/dll/ntdll/csr/capture.c
@@ -101,6 +101,9 @@ CsrAllocateCaptureBuffer(IN ULONG ArgumentCount,
     /* Align it to a 4-byte boundary */
     BufferSize = (BufferSize + 3) & ~3;
 
+    /* Add the size of the alignment padding for each argument */
+    BufferSize += ArgumentCount * 3;
+
     /* Allocate memory from the port heap */
     CaptureBuffer = RtlAllocateHeap(CsrPortHeap, HEAP_ZERO_MEMORY, BufferSize);
     if (CaptureBuffer == NULL) return NULL;