diff --git a/tests/ahci-test.c b/tests/ahci-test.c
index 77d0f97..b21d4ad 100644
--- a/tests/ahci-test.c
+++ b/tests/ahci-test.c
@@ -657,12 +657,10 @@ static void ahci_test_port_spec(AHCIQState *ahci, uint8_t port)
  */
 static void ahci_test_identify(AHCIQState *ahci)
 {
-    RegD2HFIS *d2h = g_malloc0(0x20);
-    RegD2HFIS *pio = g_malloc0(0x20);
     RegH2DFIS fis;
     AHCICommandHeader cmd;
     PRD prd;
-    uint32_t reg, data_ptr;
+    uint32_t data_ptr;
     uint16_t buff[256];
     unsigned i;
     int rc;
@@ -752,27 +750,11 @@ static void ahci_test_identify(AHCIQState *ahci)
     /* BUG: we expect AHCI_PX_IS_DPS to be set. */
     ahci_port_check_interrupts(ahci, i, AHCI_PX_IS_DHRS | AHCI_PX_IS_PSS);
     ahci_port_check_nonbusy(ahci, i, cx);
-
     /* Investigate the CMD, assert that we read 512 bytes */
-    ahci_get_command_header(ahci, i, cx, &cmd);
-    g_assert_cmphex(512, ==, cmd.prdbc);
-
+    ahci_port_check_cmd_sanity(ahci, i, cx, 512);
     /* Investigate FIS responses */
-    memread(ahci->port[i].fb + 0x20, pio, 0x20);
-    memread(ahci->port[i].fb + 0x40, d2h, 0x20);
-    g_assert_cmphex(pio->fis_type, ==, 0x5f);
-    g_assert_cmphex(d2h->fis_type, ==, 0x34);
-    g_assert_cmphex(pio->flags, ==, d2h->flags);
-    g_assert_cmphex(pio->status, ==, d2h->status);
-    g_assert_cmphex(pio->error, ==, d2h->error);
-
-    reg = ahci_px_rreg(ahci, i, AHCI_PX_TFD);
-    g_assert_cmphex((reg & AHCI_PX_TFD_ERR), ==, pio->error);
-    g_assert_cmphex((reg & AHCI_PX_TFD_STS), ==, pio->status);
-    /* The PIO Setup FIS contains a "bytes read" field, which is a
-     * 16-bit value. The Physical Region Descriptor Byte Count is
-     * 32-bit, but for small transfers using one PRD, it should match. */
-    g_assert_cmphex(le16_to_cpu(pio->res4), ==, cmd.prdbc);
+    ahci_port_check_d2h_sanity(ahci, i, cx);
+    ahci_port_check_pio_sanity(ahci, i, cx, 512);
 
     /* Last, but not least: Investigate the IDENTIFY response data. */
     memread(data_ptr, &buff, 512);
@@ -789,9 +771,6 @@ static void ahci_test_identify(AHCIQState *ahci)
     string_bswap16(&buff[23], 8);
     rc = memcmp(&buff[23], "version ", 8);
     g_assert_cmphex(rc, ==, 0);
-
-    g_free(d2h);
-    g_free(pio);
 }
 
 /******************************************************************************/
diff --git a/tests/libqos/ahci.c b/tests/libqos/ahci.c
index 0016aad..924b9f0 100644
--- a/tests/libqos/ahci.c
+++ b/tests/libqos/ahci.c
@@ -365,6 +365,53 @@ void ahci_port_check_nonbusy(AHCIQState *ahci, uint8_t px, uint8_t cx)
     ASSERT_BIT_CLEAR(reg, AHCI_PX_TFD_STS_DRQ);
 }
 
+void ahci_port_check_d2h_sanity(AHCIQState *ahci, uint8_t px, uint8_t cx)
+{
+    RegD2HFIS *d2h = g_malloc0(0x20);
+    uint32_t reg;
+
+    memread(ahci->port[px].fb + 0x40, d2h, 0x20);
+    g_assert_cmphex(d2h->fis_type, ==, 0x34);
+
+    reg = ahci_px_rreg(ahci, px, AHCI_PX_TFD);
+    g_assert_cmphex((reg & AHCI_PX_TFD_ERR) >> 8, ==, d2h->error);
+    g_assert_cmphex((reg & AHCI_PX_TFD_STS), ==, d2h->status);
+
+    g_free(d2h);
+}
+
+void ahci_port_check_pio_sanity(AHCIQState *ahci, uint8_t px,
+                                uint8_t cx, size_t buffsize)
+{
+    PIOSetupFIS *pio = g_malloc0(0x20);
+
+    /* We cannot check the Status or E_Status registers, becuase
+     * the status may have again changed between the PIO Setup FIS
+     * and the conclusion of the command with the D2H Register FIS. */
+    memread(ahci->port[px].fb + 0x20, pio, 0x20);
+    g_assert_cmphex(pio->fis_type, ==, 0x5f);
+
+    /* BUG: PIO Setup FIS as utilized by QEMU tries to fit the entire
+     * transfer size in a uint16_t field. The maximum transfer size can
+     * eclipse this; the field is meant to convey the size of data per
+     * each Data FIS, not the entire operation as a whole. For now,
+     * we will sanity check the broken case where applicable. */
+    if (buffsize <= UINT16_MAX) {
+        g_assert_cmphex(le16_to_cpu(pio->tx_count), ==, buffsize);
+    }
+
+    g_free(pio);
+}
+
+void ahci_port_check_cmd_sanity(AHCIQState *ahci, uint8_t px,
+                                uint8_t cx, size_t buffsize)
+{
+    AHCICommandHeader cmd;
+
+    ahci_get_command_header(ahci, px, cx, &cmd);
+    g_assert_cmphex(buffsize, ==, cmd.prdbc);
+}
+
 /* Get the #cx'th command of port #px. */
 void ahci_get_command_header(AHCIQState *ahci, uint8_t px,
                              uint8_t cx, AHCICommandHeader *cmd)
diff --git a/tests/libqos/ahci.h b/tests/libqos/ahci.h
index 7c504a5..3b4e1ef 100644
--- a/tests/libqos/ahci.h
+++ b/tests/libqos/ahci.h
@@ -283,25 +283,44 @@ typedef struct RegD2HFIS {
     uint8_t status;
     uint8_t error;
     /* DW1 */
-    uint8_t lba_low;
-    uint8_t lba_mid;
-    uint8_t lba_high;
+    uint8_t lba_lo[3];
     uint8_t device;
     /* DW2 */
-    uint8_t lba3;
-    uint8_t lba4;
-    uint8_t lba5;
-    uint8_t res1;
+    uint8_t lba_hi[3];
+    uint8_t res0;
     /* DW3 */
     uint16_t count;
-    uint8_t res2;
-    uint8_t res3;
+    uint16_t res1;
     /* DW4 */
-    uint16_t res4;
-    uint16_t res5;
+    uint32_t res2;
 } __attribute__((__packed__)) RegD2HFIS;
 
 /**
+ * Register device-to-host FIS structure;
+ * PIO Setup variety.
+ */
+typedef struct PIOSetupFIS {
+    /* DW0 */
+    uint8_t fis_type;
+    uint8_t flags;
+    uint8_t status;
+    uint8_t error;
+    /* DW1 */
+    uint8_t lba_lo[3];
+    uint8_t device;
+    /* DW2 */
+    uint8_t lba_hi[3];
+    uint8_t res0;
+    /* DW3 */
+    uint16_t count;
+    uint8_t res1;
+    uint8_t e_status;
+    /* DW4 */
+    uint16_t tx_count;
+    uint16_t res2;
+} __attribute__((__packed__)) PIOSetupFIS;
+
+/**
  * Register host-to-device FIS structure.
  */
 typedef struct RegH2DFIS {
@@ -311,14 +330,10 @@ typedef struct RegH2DFIS {
     uint8_t command;
     uint8_t feature_low;
     /* DW1 */
-    uint8_t lba_low;
-    uint8_t lba_mid;
-    uint8_t lba_high;
+    uint8_t lba_lo[3];
     uint8_t device;
     /* DW2 */
-    uint8_t lba3;
-    uint8_t lba4;
-    uint8_t lba5;
+    uint8_t lba_hi[3];
     uint8_t feature_high;
     /* DW3 */
     uint16_t count;
@@ -437,6 +452,11 @@ void ahci_port_check_error(AHCIQState *ahci, uint8_t px);
 void ahci_port_check_interrupts(AHCIQState *ahci, uint8_t px,
                                 uint32_t intr_mask);
 void ahci_port_check_nonbusy(AHCIQState *ahci, uint8_t px, uint8_t cx);
+void ahci_port_check_d2h_sanity(AHCIQState *ahci, uint8_t px, uint8_t cx);
+void ahci_port_check_pio_sanity(AHCIQState *ahci, uint8_t px,
+                                uint8_t cx, size_t buffsize);
+void ahci_port_check_cmd_sanity(AHCIQState *ahci, uint8_t px,
+                                uint8_t cx, size_t buffsize);
 void ahci_get_command_header(AHCIQState *ahci, uint8_t px,
                              uint8_t cx, AHCICommandHeader *cmd);
 void ahci_set_command_header(AHCIQState *ahci, uint8_t px,
