diff --git a/src/company_gui.cpp b/src/company_gui.cpp
index 79cede9573..ea0c9df394 100644
--- a/src/company_gui.cpp
+++ b/src/company_gui.cpp
@@ -795,7 +795,7 @@ public:
 		/* Position scrollbar to selected group */
 		for (uint i = 0; i < this->rows; i++) {
 			if (this->groups[i]->index == sel) {
-				this->vscroll->SetPosition(Clamp(i - this->vscroll->GetCapacity() / 2, 0, std::max(this->vscroll->GetCount() - this->vscroll->GetCapacity(), 0)));
+				this->vscroll->SetPosition(i - this->vscroll->GetCapacity() / 2);
 				break;
 			}
 		}
diff --git a/src/script/script_gui.cpp b/src/script/script_gui.cpp
index 8c9a1abcc7..1a1bca2822 100644
--- a/src/script/script_gui.cpp
+++ b/src/script/script_gui.cpp
@@ -866,9 +866,7 @@ struct ScriptDebugWindow : public Window {
 		}
 		if (this->autoscroll) {
 			int scroll_pos = std::max(0, log->used - this->vscroll->GetCapacity());
-			if (scroll_pos != this->vscroll->GetPosition()) {
-				this->vscroll->SetPosition(scroll_pos);
-
+			if (this->vscroll->SetPosition(scroll_pos)) {
 				/* We need a repaint */
 				this->SetWidgetDirty(WID_SCRD_SCROLLBAR);
 				this->SetWidgetDirty(WID_SCRD_LOG_PANEL);
diff --git a/src/widget_type.h b/src/widget_type.h
index 8c05a321f7..078aa49b10 100644
--- a/src/widget_type.h
+++ b/src/widget_type.h
@@ -746,10 +746,8 @@ public:
 	 */
 	bool SetPosition(int position)
 	{
-		assert(position >= 0);
-		assert(this->count <= this->cap ? (position == 0) : (position + this->cap <= this->count));
 		uint16 old_pos = this->pos;
-		this->pos = position;
+		this->pos = Clamp(position, 0, std::max(this->count - this->cap, 0));
 		return this->pos != old_pos;
 	}
 
@@ -768,7 +766,7 @@ public:
 			case SS_BIG:   difference *= this->cap; break;
 			default: break;
 		}
-		return this->SetPosition(Clamp(this->pos + difference, 0, std::max(this->count - this->cap, 0)));
+		return this->SetPosition(this->pos + difference);
 	}
 
 	/**