diff --git a/pyqtgraph/graphicsItems/PlotCurveItem.py b/pyqtgraph/graphicsItems/PlotCurveItem.py
index 1b3197b5..763eeb45 100644
--- a/pyqtgraph/graphicsItems/PlotCurveItem.py
+++ b/pyqtgraph/graphicsItems/PlotCurveItem.py
@@ -580,6 +580,7 @@ class PlotCurveItem(GraphicsObject):
                 if pen.isCosmetic() and width < 1:
                     width = 1
                 gl.glPointSize(width)
+                gl.glLineWidth(width)
                 gl.glEnable(gl.GL_LINE_SMOOTH)
                 gl.glEnable(gl.GL_BLEND)
                 gl.glBlendFunc(gl.GL_SRC_ALPHA, gl.GL_ONE_MINUS_SRC_ALPHA)