diff --git a/src/lib/ics.test.ts b/src/lib/ics.test.ts
index ea7d583..db45b74 100644
--- a/src/lib/ics.test.ts
+++ b/src/lib/ics.test.ts
@@ -128,4 +128,23 @@ describe("exportICS", () => {
     const eventCount = (ics.match(/BEGIN:VEVENT/g) || []).length;
     expect(eventCount).toBe(1);
   });
+
+  it("correctly exports section when section numbers have gaps", () => {
+    // Simulate real Caltech data where section numbers skip (e.g., 1, 2, 4, 5)
+    const section1 = makeSection(1, "M 09:00 - 09:55", "Baxter 101");
+    const section2 = makeSection(2, "T 10:00 - 10:55", "Baxter 102");
+    const section4 = makeSection(4, "W 11:00 - 11:55", "Sloan 151");
+    const section5 = makeSection(5, "R 13:00 - 13:55", "Sloan 152");
+    const courseData = makeCourseData(1, "CS 1", [section1, section2, section4, section5]);
+
+    // sectionId 2 = array index 2 = section number 4 (Wednesday)
+    const course = makeCourse(courseData, { sectionId: 2 });
+
+    const ics = exportICS("sp2026", [course]);
+
+    expect(ics).toContain("BEGIN:VEVENT");
+    const eventCount = (ics.match(/BEGIN:VEVENT/g) || []).length;
+    expect(eventCount).toBe(1);
+    expect(ics).toContain("LOCATION:Sloan 151");
+  });
 });
diff --git a/src/lib/ics.ts b/src/lib/ics.ts
index 0779ac7..1caf0a4 100644
--- a/src/lib/ics.ts
+++ b/src/lib/ics.ts
@@ -63,28 +63,27 @@ export function exportICS(term: string, courses: CourseStorage[]): string {
 
   // Flatten the courses and parse times with start and end times, matching locations
   const parsedEvents = courses
-    .filter(course => course.enabled)
+    .filter(course => course.enabled && course.sectionId !== null)
     .flatMap(course => {
-      return course.courseData.sections
-        .filter(section => section.number - 1 === course.sectionId) // Filter by selected section
-        .flatMap(section => {
-          const times = section.times.split('\n'); // Split multiple times on newline
-          const locations = section.locations.split('\n'); // Split multiple locations on newline
-
-          // Zip times and locations together
-          return times.flatMap((time, index) => {
-            const location = locations[index] || 'Unknown'; // Match time with corresponding location
-            const [days, startTime, , endTime] = time.split(' '); // Separate days and time range
-            if (days === 'A') return []; // skip to-be-announced times
-            
-            return days.split('').map(day => ({
-              name: course.courseData.number, // Use course number for the title
-              location, // Set the matched location for this time
-              startTime: getFirstOccurrence(termStartDate, day, startTime),
-              endTime: getFirstOccurrence(termStartDate, day, endTime) // Parse the end time
-            }));
-          });
-        });
+      const section = course.courseData.sections[course.sectionId!];
+      if (!section) return [];
+
+      const times = section.times.split('\n'); // Split multiple times on newline
+      const locations = section.locations.split('\n'); // Split multiple locations on newline
+
+      // Zip times and locations together
+      return times.flatMap((time, index) => {
+        const location = locations[index] || 'Unknown'; // Match time with corresponding location
+        const [days, startTime, , endTime] = time.split(' '); // Separate days and time range
+        if (days === 'A') return []; // skip to-be-announced times
+
+        return days.split('').map(day => ({
+          name: course.courseData.number, // Use course number for the title
+          location, // Set the matched location for this time
+          startTime: getFirstOccurrence(termStartDate, day, startTime),
+          endTime: getFirstOccurrence(termStartDate, day, endTime) // Parse the end time
+        }));
+      });
     });
 
   // Create a basic ICS header using stable floating local times.