diff --git a/devices/floppy/swim3.cpp b/devices/floppy/swim3.cpp
index b6333b3..c2da74e 100644
--- a/devices/floppy/swim3.cpp
+++ b/devices/floppy/swim3.cpp
@@ -171,10 +171,12 @@ void Swim3Ctrl::write(uint8_t reg_offset, uint8_t value)
 
 void Swim3Ctrl::update_irq()
 {
-    uint8_t new_irq = !!(this->int_flags & this->int_mask);
-    if (new_irq != this->irq) {
-        this->irq = new_irq;
-        this->int_ctrl->ack_int(this->irq_id, new_irq);
+    if (this->mode_reg & SWIM3_INT_ENA) {
+        uint8_t new_irq = !!(this->int_flags & this->int_mask);
+        if (new_irq != this->irq) {
+            this->irq = new_irq;
+            this->int_ctrl->ack_int(this->irq_id, new_irq);
+        }
     }
 }
 
diff --git a/devices/floppy/swim3.h b/devices/floppy/swim3.h
index d6050bc..2b5a154 100644
--- a/devices/floppy/swim3.h
+++ b/devices/floppy/swim3.h
@@ -55,6 +55,7 @@ enum Swim3Reg : uint8_t {
 
 /** Mode register bits. */
 enum {
+    SWIM3_INT_ENA = 0x01,
     SWIM3_GO      = 0x08,
     SWIM3_WR_MODE = 0x10,
     SWIM3_GO_STEP = 0x80,