diff --git a/src/frontend/inp.c b/src/frontend/inp.c
index 4affda156..90fdd0f61 100644
--- a/src/frontend/inp.c
+++ b/src/frontend/inp.c
@@ -1498,7 +1498,7 @@ create_circbyline(char *line)
     if (linec < memlen) {
         if (ciprefix(".end", line) && (line[4] == '\0' || isspace_c(line[4]))) {
             circarray[linec] = NULL;
-            inp_spsource(fp, FALSE, "", TRUE);
+            inp_spsource(fp, FALSE, NULL, TRUE);
             linec = 0;
         }
     }