diff --git a/src/if_python3.c b/src/if_python3.c
index da0867b..daaf689 100644
--- a/src/if_python3.c
+++ b/src/if_python3.c
@@ -1114,7 +1114,7 @@
 	    return NULL;
 
 	if (PySlice_GetIndicesEx((PyObject *)idx,
-	      (Py_ssize_t)((BufferObject *)(self))->buf->b_ml.ml_line_count+1,
+	      (Py_ssize_t)((BufferObject *)(self))->buf->b_ml.ml_line_count,
 	      &start, &stop,
 	      &step, &slicelen) < 0)
 	{
@@ -1146,7 +1146,7 @@
 	    return -1;
 
 	if (PySlice_GetIndicesEx((PyObject *)idx,
-	      (Py_ssize_t)((BufferObject *)(self))->buf->b_ml.ml_line_count+1,
+	      (Py_ssize_t)((BufferObject *)(self))->buf->b_ml.ml_line_count,
 	      &start, &stop,
 	      &step, &slicelen) < 0)
 	{