diff --git a/index.ts b/index.ts
index 823d58d..06ea916 100644
--- a/index.ts
+++ b/index.ts
@@ -1,17 +1,19 @@
+import {notNull} from "@softwareventures/nullable";
+
 export type Table = string[][];
 
 export type ReadonlyTable = ReadonlyArray<ReadonlyArray<string>>;
 
 export function* tableToRecords(table: ReadonlyTable): Iterable<Record<string, string>> {
-    const header = table[0];
+    const header = notNull(table[0]);
 
     for (let i = 1; i < table.length; ++i) {
-        const row = table[i];
+        const row = notNull(table[i]);
         const record: Record<string, string> = {};
 
         for (let j = 0; j < row.length && j < header.length; ++j) {
-            const name = header[j];
-            record[name] = row[j];
+            const name = notNull(header[j]);
+            record[name] = notNull(row[j]);
         }
 
         yield record;
@@ -23,14 +25,14 @@ export function recordsToTable(records: ReadonlyArray<Readonly<Record<string, st
         return [];
     }
 
-    const headers = Object.keys(records[0]);
+    const headers = Object.keys(notNull(records[0]));
 
     return [headers]
         .concat(records
             .map(record => headers
                 .map(header => {
                     if (header in record) {
-                        return record[header];
+                        return notNull(record[header]);
                     } else {
                         throw new Error("Inconsistent records.");
                     }
diff --git a/package.json b/package.json
index 33f90a3..b5c87b4 100644
--- a/package.json
+++ b/package.json
@@ -25,6 +25,7 @@
     "node": "^14 || ^16 || >=18"
   },
   "dependencies": {
+    "@softwareventures/nullable": "^3.0.0",
     "tslib": "^1.9.3 || ^2.0.0 || ^2.1.0"
   },
   "devDependencies": {
diff --git a/yarn.lock b/yarn.lock
index 005696e..2f43729 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -481,6 +481,13 @@
     lodash "^4.17.4"
     read-pkg-up "^7.0.0"
 
+"@softwareventures/nullable@^3.0.0":
+  version "3.0.0"
+  resolved "https://registry.yarnpkg.com/@softwareventures/nullable/-/nullable-3.0.0.tgz#979045c99e7c8a9055cb25c3c5cb5b9edfc50085"
+  integrity sha512-kgYOGJHzgZl0QGqMqbRe34i5VaRQUsG+X9AcblJL1lGDq+npLsCS974VSJmOBxnSqIQ5dcgah+zBxHndH8qzfg==
+  dependencies:
+    tslib "2.4.0"
+
 "@softwareventures/semantic-release-config@3.0.0":
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/@softwareventures/semantic-release-config/-/semantic-release-config-3.0.0.tgz#11bc1edbe4de1cd37a79dcf050d5be6e8467ada0"