diff --git a/src/eval.c b/src/eval.c
index 7f90954..1aa0eae 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -3089,7 +3089,7 @@
 		rettv->vval.v_number = 0;
 	    else if (type == EXPR_LSHIFT)
 		rettv->vval.v_number =
-				    rettv->vval.v_number << var2.vval.v_number;
+		      (uvarnumber_T)rettv->vval.v_number << var2.vval.v_number;
 	    else
 		rettv->vval.v_number =
 		      (uvarnumber_T)rettv->vval.v_number >> var2.vval.v_number;