diff --git a/OSBindings/Mac/Clock SignalTests/MasterSystemVDPTests.mm b/OSBindings/Mac/Clock SignalTests/MasterSystemVDPTests.mm
index ec5c36587..5ef2d72b5 100644
--- a/OSBindings/Mac/Clock SignalTests/MasterSystemVDPTests.mm	
+++ b/OSBindings/Mac/Clock SignalTests/MasterSystemVDPTests.mm	
@@ -57,6 +57,10 @@
 	// Get time until interrupt.
 	int time_until_interrupt = vdp.get_time_until_interrupt().as_int() - 1;
 
+	// Check that an interrupt is now scheduled.
+	NSAssert(time_until_interrupt != -2, @"No interrupt scheduled");
+	NSAssert(time_until_interrupt > 0, @"Interrupt is scheduled in the past");
+
 	// Check interrupt flag isn't set prior to the reported time.
 	vdp.run_for(HalfCycles(time_until_interrupt));
 	NSAssert(!vdp.get_interrupt_line(), @"Interrupt line went active early [1]");
@@ -79,4 +83,37 @@
 	NSAssert(vdp.get_interrupt_line(), @"Interrupt line wasn't set when promised [2]");
 }
 
+- (void)testFirstLineInterrupt {
+	TI::TMS::TMS9918 vdp(TI::TMS::Personality::SMSVDP);
+
+	// Disable end-of-frame interrupts, enable line interrupts, set an interrupt to occur every line.
+	vdp.set_register(1, 0x00);
+	vdp.set_register(1, 0x81);
+
+	vdp.set_register(1, 0x10);
+	vdp.set_register(1, 0x80);
+
+	vdp.set_register(1, 0);
+	vdp.set_register(1, 0x8a);
+
+	// Advance to outside of the counted area.
+	while(vdp.get_current_line() < 200) vdp.run_for(Cycles(228));
+
+	// Clear the pending interrupt and ask about the next one (i.e. the first one).
+	vdp.get_register(1);
+	int time_until_interrupt = vdp.get_time_until_interrupt().as_int() - 1;
+
+	// Check that an interrupt is now scheduled.
+	NSAssert(time_until_interrupt != -2, @"No interrupt scheduled");
+	NSAssert(time_until_interrupt > 0, @"Interrupt is scheduled in the past");
+
+	// Check interrupt flag isn't set prior to the reported time.
+	vdp.run_for(HalfCycles(time_until_interrupt));
+	NSAssert(!vdp.get_interrupt_line(), @"Interrupt line went active early");
+
+	// Check interrupt flag is set at the reported time.
+	vdp.run_for(HalfCycles(1));
+	NSAssert(vdp.get_interrupt_line(), @"Interrupt line wasn't set when promised");
+}
+
 @end