diff --git a/core_common.c b/core_common.c
index 7ac0aa8..b665cfe 100644
--- a/core_common.c
+++ b/core_common.c
@@ -51,13 +51,12 @@ int mx_sg_locate(struct sg_table *sgt, size_t byte_offset,
 	return -EINVAL;
 }
 
-/* First PRP chunk length within an SG entry starting at intra_off; truncates so subsequent chunks
- * land on dma_size boundaries.  Returns dma_size when already aligned.  Works for arbitrary
- * dma_size (compiler folds the modulo to a bitmask when dma_size is a known power of 2). */
+/* First PRP chunk length at (sg, intra_off): distance to the next dma_size boundary of the
+ * mapped DMA address.  Computed from sg_dma_address(), not the CPU page offset — the device
+ * splits by the address it receives, and SWIOTLB may not preserve the low address bits. */
 size_t mx_prp_first_chunk_len(struct scatterlist *sg, size_t intra_off, size_t dma_size)
 {
-	size_t off_in_page = (sg->offset + intra_off) & (PAGE_SIZE - 1);
-	size_t rem = off_in_page % dma_size;
+	size_t rem = (sg_dma_address(sg) + intra_off) % dma_size;
 
 	return rem ? (dma_size - rem) : dma_size;
 }
diff --git a/core_v2.c b/core_v2.c
index 4217e86..b0a7c07 100644
--- a/core_v2.c
+++ b/core_v2.c
@@ -226,11 +226,6 @@ static const struct mx_queue_ops v2_queue_ops = {
 #define SINGLE_DMA_SIZE		PAGE_SIZE
 #define NUM_OF_DESC_PER_LIST	(SINGLE_DMA_SIZE / sizeof(uint64_t))
 
-/* create_mx_command_sg branches on host page count (split_pages_nr) but emits PRP entries of dma_size
- * (= SINGLE_DMA_SIZE).  Branching is correct only while these match. */
-static_assert(SINGLE_DMA_SIZE == PAGE_SIZE,
-	      "v2 PRP branching in create_mx_command_sg assumes SINGLE_DMA_SIZE == PAGE_SIZE");
-
 static struct mx_command *alloc_mx_command(struct mx_transfer *transfer, int opcode)
 {
 	struct mx_command *comm = (struct mx_command *)transfer->cmd_inline;
@@ -251,9 +246,7 @@ static void *create_mx_command_sg(struct mx_pci_dev *mx_pdev, struct mx_transfer
 	struct sg_table *sgt = &transfer->sg_ctx->sgt;
 	struct scatterlist *sg = NULL;
 	size_t intra_off = 0;
-	unsigned int slice_offset_in_page =
-		offset_in_page((uintptr_t)transfer->sg_ctx->user_addr + transfer->sg_byte_offset);
-	int split_pages_nr = DIV_ROUND_UP(slice_offset_in_page + transfer->size, PAGE_SIZE);
+	size_t desc_cnt;
 	int ret;
 
 	comm = alloc_mx_command(transfer, opcode);
@@ -274,19 +267,22 @@ static void *create_mx_command_sg(struct mx_pci_dev *mx_pdev, struct mx_transfer
 		return NULL;
 	}
 
-	if (split_pages_nr == 1) {
+	/* Branch on the DMA-side entry count, not host page count (alignments can differ). */
+	desc_cnt = mx_get_total_desc_count(sg, intra_off, transfer->size, SINGLE_DMA_SIZE, false);
+
+	if (desc_cnt == 1) {
 		comm->prp_entry2 = 0;
-	} else if (split_pages_nr == 2) {
+	} else if (desc_cnt == 2) {
 		size_t first_len = mx_prp_first_chunk_len(sg, intra_off, SINGLE_DMA_SIZE);
 
-		/* Second PRP entry points to the page after the first chunk. */
+		/* Second PRP entry points to the chunk after the first. */
 		if (intra_off + first_len < sg_dma_len(sg)) {
 			comm->prp_entry2 = comm->prp_entry1 + first_len;
 		} else {
 			struct scatterlist *next = sg_next(sg);
 
 			if (!next) {
-				pr_warn("sg_next NULL in 2-page path (id=%u)\n", transfer->id);
+				pr_warn("sg_next NULL in 2-entry path (id=%u)\n", transfer->id);
 				return NULL;
 			}
 			comm->prp_entry2 = sg_dma_address(next);
diff --git a/mx_dma.h b/mx_dma.h
index efacd28..e2db9e6 100644
--- a/mx_dma.h
+++ b/mx_dma.h
@@ -423,8 +423,8 @@ uint64_t mx_desc_list_init(struct mx_pci_dev *mx_pdev, struct mx_transfer *trans
 int mx_sg_locate(struct sg_table *sgt, size_t byte_offset,
 		 struct scatterlist **out_sg, size_t *out_intra);
 
-/* First PRP chunk length when starting intra_off bytes into an SG entry; truncates so subsequent
- * chunks land on dma_size boundaries.  Returns dma_size when already aligned.  See core_common.c. */
+/* First PRP chunk length at (sg, intra_off); splits fall on dma_size boundaries of the mapped
+ * DMA address.  See core_common.c. */
 size_t mx_prp_first_chunk_len(struct scatterlist *sg, size_t intra_off, size_t dma_size);
 
 void mx_stop_queue_threads(struct mx_pci_dev *mx_pdev);