diff --git a/Outputs/OpenGL/ScanTarget.cpp b/Outputs/OpenGL/ScanTarget.cpp
index 33443532e..606c57531 100644
--- a/Outputs/OpenGL/ScanTarget.cpp
+++ b/Outputs/OpenGL/ScanTarget.cpp
@@ -228,11 +228,8 @@ void ScanTarget::end_data(size_t actual_length) {
 		&write_area_texture_[size_t(write_pointers_.write_area) * data_type_size_],
 		data_type_size_);
 
-	// The write area was allocated in the knowledge that there's sufficient
-	// distance left on the current line, but there's a risk of exactly filling
-	// the final line, in which case this should wrap back to 0.
+	// Advance to the end of the current run.
 	write_pointers_.write_area += actual_length + 1;
-	write_pointers_.write_area %= (write_area_texture_.size() / data_type_size_);
 
 	// Also bookend the end.
 	memcpy(
@@ -240,6 +237,11 @@ void ScanTarget::end_data(size_t actual_length) {
 		&write_area_texture_[size_t(write_pointers_.write_area - 2) * data_type_size_],
 		data_type_size_);
 
+	// The write area was allocated in the knowledge that there's sufficient
+	// distance left on the current line, but there's a risk of exactly filling
+	// the final line, in which case this should wrap back to 0.
+	write_pointers_.write_area %= (write_area_texture_.size() / data_type_size_);
+
 	// Record that no further end_data calls are expected.
 	data_is_allocated_ = false;
 }