diff --git a/semver/_shared.ts b/semver/_shared.ts
index f31f5366e9d53..d6fe6b1108140 100644
--- a/semver/_shared.ts
+++ b/semver/_shared.ts
@@ -185,7 +185,10 @@ export function parseBuild(buildmetadata: string) {
   return buildmetadata.split(".").filter(Boolean);
 }
 
-export function parseNumber(input: string, errorMessage: string) {
+export function parseNumber(input: string | undefined, errorMessage: string) {
+  if (input === undefined) {
+    return 0;
+  }
   const number = Number(input);
   if (!isValidNumber(number)) throw new TypeError(errorMessage);
   return number;
diff --git a/semver/parse_range.ts b/semver/parse_range.ts
index 94c88d5c0c0b1..c429d1a027607 100644
--- a/semver/parse_range.ts
+++ b/semver/parse_range.ts
@@ -5,7 +5,7 @@ import { OPERATOR_XRANGE_REGEXP, XRANGE } from "./_shared.ts";
 import { parseComparator } from "./_parse_comparator.ts";
 import { parseBuild, parsePrerelease } from "./_shared.ts";
 
-function isWildcard(id: string): boolean {
+function isWildcard(id?: string): boolean {
   return !id || id.toLowerCase() === "x" || id === "*";
 }
 
@@ -50,9 +50,9 @@ function parseHyphenRange(range: string) {
   if (isWildcard(rightGroups.major)) {
     to = "";
   } else if (isWildcard(rightGroups.minor)) {
-    to = `<${+rightGroups.major + 1}.0.0`;
+    to = `<${+rightGroups.major! + 1}.0.0`;
   } else if (isWildcard(rightGroups.patch)) {
-    to = `<${rightGroups.major}.${+rightGroups.minor + 1}.0`;
+    to = `<${rightGroups.major}.${+rightGroups.minor! + 1}.0`;
   } else if (rightGroups.prerelease) {
     to =
       `<=${rightGroups.major}.${rightGroups.minor}.${rightGroups.patch}-${rightGroups.prerelease}`;
diff --git a/semver/range_intersects.ts b/semver/range_intersects.ts
index 9dc802c40f701..471ef54d42b32 100644
--- a/semver/range_intersects.ts
+++ b/semver/range_intersects.ts
@@ -12,7 +12,7 @@ function rangesSatisfiable(ranges: Range[]): boolean {
 function comparatorsSatisfiable(comparators: Comparator[]): boolean {
   // Comparators are satisfiable if they all intersect with each other
   for (let i = 0; i < comparators.length - 1; i++) {
-    const c0 = comparators[i];
+    const c0 = comparators[i]!;
     for (const c1 of comparators.slice(i + 1)) {
       if (!comparatorIntersects(c0, c1)) {
         return false;