diff --git a/allscripts(deprecated).js b/allscripts(deprecated).js
index e360c3f..341b7ec 100644
--- a/allscripts(deprecated).js
+++ b/allscripts(deprecated).js
@@ -69,6 +69,12 @@ register('fill', function (pat) {
       // Find the next onset, to use as an offset
       const next = onsets.find(onset => onset.gte(hap.whole.end));
 
+      // If there is no next onset, the query window is not large enough.
+      // We bail out to avoid a crash.
+      if (next === undefined) {
+        continue;
+      }
+
       // Ignore if the part ended before the original query, and hasn't expanded inside
       if (next.lte(state.span.begin)) {
         continue;
diff --git a/prebake.strudel b/prebake.strudel
index 30d8504..b1a672c 100644
--- a/prebake.strudel
+++ b/prebake.strudel
@@ -156,6 +156,12 @@ register('fill', function (pat) {
       // Find the next onset, to use as an offset
       const next = onsets.find(onset => onset.gte(hap.whole.end));
 
+      // If there is no next onset, the query window is not large enough.
+      // We bail out to avoid a crash.
+      if (next === undefined) {
+        continue;
+      }
+
       // Ignore if the part ended before the original query, and hasn't expanded inside
       if (next.lte(state.span.begin)) {
         continue;