diff --git a/src/include/86box/pci.h b/src/include/86box/pci.h
index 8483eb417..d2348ba02 100644
--- a/src/include/86box/pci.h
+++ b/src/include/86box/pci.h
@@ -115,6 +115,11 @@
 /* PCI MIRQ lines (currently 8, this many are needed by the ALi M1543(C). */
 #define PCI_MIRQS_NUM             8
 #define PCI_MIRQ_MAX              (PCI_MIRQS_NUM - 1)
+/* The base for internal IRQ lines accepted by pci_irq(). */
+#define PCI_IIRQ_BASE             0x80
+/* PCI direct IRQ lines - always at 4 per the PCI specification. */
+#define PCI_IIRQS_NUM             4
+#define PCI_IIRQ_MAX              (PCI_IIRQS_NUM - 1)
 /* The base for direct IRQ lines accepted by pci_irq(). */
 #define PCI_DIRQ_BASE             0xf0
 /* PCI direct IRQ lines (currently 16 because we only emulate the legacy PIC). */
@@ -148,12 +153,16 @@
 
 #define pci_set_mirq(mirq, level, irq_state) \
         pci_irq(PCI_MIRQ_BASE | (mirq), 0, level, 1, irq_state)
+#define pci_set_iirq(pci_int, irq_state) \
+        pci_irq(PCI_IIRQ_BASE | 0, pci_int, 0, 1, irq_state)
 #define pci_set_dirq(irq, irq_state) \
         pci_irq(PCI_DIRQ_BASE | (irq), 0, 1, 1, irq_state)
 #define pci_set_irq(slot, pci_int, irq_state) \
         pci_irq(slot, pci_int, 0, 1, irq_state)
 #define pci_clear_mirq(mirq, level, irq_state) \
         pci_irq(PCI_MIRQ_BASE | (mirq), 0, level, 0, irq_state)
+#define pci_clear_iirq(pci_int, irq_state) \
+        pci_irq(PCI_IIRQ_BASE | 0, pci_int, 0, 0, irq_state)
 #define pci_clear_dirq(dirq, irq_state) \
         pci_irq(PCI_DIRQ_BASE | (irq), 0, 1, 0, irq_state)
 #define pci_clear_irq(slot, pci_int, irq_state) \
diff --git a/src/pci.c b/src/pci.c
index 13b780050..266be4396 100644
--- a/src/pci.c
+++ b/src/pci.c
@@ -204,6 +204,19 @@ pci_irq(uint8_t slot, uint8_t pci_int, int level, int set, uint8_t *irq_state)
                 }
             }
             break;
+        case (PCI_IIRQ_BASE | 0x00) ... (PCI_IIRQ_BASE | PCI_IIRQ_MAX):
+            /* PCI internal routing. */
+            if (!last_pci_card || (pci_flags & FLAG_NO_IRQ_STEERING))
+                return;
+
+            irq_routing = (pci_int_index - PCI_INTA) & PCI_IRQ_MAX;
+
+            irq_line    = pci_irqs[irq_routing];
+
+            /* Ignore what was provided to us as a parameter and override it with whatever
+               the chipset is set to. */
+            level       = !!pci_irq_level[irq_routing];
+            break;
         case (PCI_MIRQ_BASE | 0x00) ... (PCI_MIRQ_BASE | PCI_MIRQ_MAX):
             /* MIRQ */
             slot &= PCI_MIRQ_MAX;