diff --git a/src/evalbuffer.c b/src/evalbuffer.c
index 3004415..4ca68c8 100644
--- a/src/evalbuffer.c
+++ b/src/evalbuffer.c
@@ -391,7 +391,7 @@
     // new buffer.
     if (buf == NULL
 	    && argvars[1].v_type != VAR_UNKNOWN
-	    && tv_get_number_chk(&argvars[1], &error) != 0
+	    && tv_get_bool_chk(&argvars[1], &error) != 0
 	    && !error
 	    && (name = tv_get_string_chk(&argvars[0])) != NULL
 	    && !error)