diff --git a/Components/9918/9918.cpp b/Components/9918/9918.cpp
index 7343aebf9..ec90b91c3 100644
--- a/Components/9918/9918.cpp
+++ b/Components/9918/9918.cpp
@@ -486,7 +486,7 @@ void TMS9918::set_register(int address, uint8_t value) {
 
 			case 10:
 				if(is_sega_vdp(personality_)) {
-					line_interrupt_target = value;
+					line_interrupt_target = low_write_;
 				}
 			break;
 
@@ -559,8 +559,12 @@ uint8_t TMS9918::get_register(int address) {
 		return generate_interrupts_ ? time_until_frame_interrupt : HalfCycles(-1);
 	}
 
-	// Figure out the number of internal cycles until the next line interrupt.
-	int local_cycles_until_line_interrupt = ((mode_timing_.line_interrupt_position - column_ + 342) % 342) + (next_line_interrupt_row - row_) * 342;
+	// Figure out the number of internal cycles until the next line interrupt, which is the amount
+	// of time to the next tick over and then next_line_interrupt_row - row_ lines further.
+	int local_cycles_until_next_tick = (mode_timing_.line_interrupt_position - column_ + 342) % 342;
+	if(!local_cycles_until_next_tick) local_cycles_until_next_tick += 342;
+
+	int local_cycles_until_line_interrupt = local_cycles_until_next_tick + (next_line_interrupt_row - row_) * 342;
 	local_cycles_until_line_interrupt <<= 2;
 	local_cycles_until_line_interrupt -= cycles_error_;
 
diff --git a/OSBindings/Mac/Clock SignalTests/MasterSystemVDPTests.mm b/OSBindings/Mac/Clock SignalTests/MasterSystemVDPTests.mm
index 0047ac20b..ec5c36587 100644
--- a/OSBindings/Mac/Clock SignalTests/MasterSystemVDPTests.mm	
+++ b/OSBindings/Mac/Clock SignalTests/MasterSystemVDPTests.mm	
@@ -59,11 +59,24 @@
 
 	// 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");
+	NSAssert(!vdp.get_interrupt_line(), @"Interrupt line went active early [1]");
 
 	// 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");
+	NSAssert(vdp.get_interrupt_line(), @"Interrupt line wasn't set when promised [1]");
+
+	// Read the status register to clear interrupt status.
+	vdp.get_register(1);
+	NSAssert(!vdp.get_interrupt_line(), @"Interrupt wasn't reset by status read");
+
+	// Check interrupt flag isn't set prior to the reported time.
+	time_until_interrupt = vdp.get_time_until_interrupt().as_int() - 1;
+	vdp.run_for(HalfCycles(time_until_interrupt));
+	NSAssert(!vdp.get_interrupt_line(), @"Interrupt line went active early [2]");
+
+	// 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 [2]");
 }
 
 @end