diff --git a/pyqtgraph/functions.py b/pyqtgraph/functions.py
index 64dad102..db22f8a3 100644
--- a/pyqtgraph/functions.py
+++ b/pyqtgraph/functions.py
@@ -1157,6 +1157,8 @@ def arrayToQPath(x, y, connect='all'):
     # decide which points are connected by lines
     if connect == 'pairs':
         connect = np.empty((n/2,2), dtype=np.int32)
+        if connect.size != n:
+            raise Exception("x,y array lengths must be multiple of 2 to use connect='pairs'")
         connect[:,0] = 1
         connect[:,1] = 0
         connect = connect.flatten()