diff --git a/lib/auth/auth.go b/lib/auth/auth.go
index 7a4d2c11c..27d1175d1 100644
--- a/lib/auth/auth.go
+++ b/lib/auth/auth.go
@@ -19,13 +19,13 @@ func NewToken(authToken string) (*Token, error) {
 		return nil, fmt.Errorf("unexpected number of items in authToken %q; got %d; want 1 or 2", authToken, len(tmp))
 	}
 	var at Token
-	accountID, err := strconv.Atoi(tmp[0])
+	accountID, err := strconv.ParseUint(tmp[0], 10, 32)
 	if err != nil {
 		return nil, fmt.Errorf("cannot parse accountID from %q: %w", tmp[0], err)
 	}
 	at.AccountID = uint32(accountID)
 	if len(tmp) > 1 {
-		projectID, err := strconv.Atoi(tmp[1])
+		projectID, err := strconv.ParseUint(tmp[1], 10, 32)
 		if err != nil {
 			return nil, fmt.Errorf("cannot parse projectID from %q: %w", tmp[1], err)
 		}
diff --git a/lib/auth/auth_test.go b/lib/auth/auth_test.go
new file mode 100644
index 000000000..81ed7f6b1
--- /dev/null
+++ b/lib/auth/auth_test.go
@@ -0,0 +1,59 @@
+package auth
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestNewTokenSuccess(t *testing.T) {
+	f := func(name string, token string, want string) {
+		t.Helper()
+		t.Run(name, func(t *testing.T) {
+			newToken, err := NewToken(token)
+			if err != nil {
+				t.Fatalf("expecting nil error")
+			}
+			got := fmt.Sprintf("%d:%d", newToken.AccountID, newToken.ProjectID)
+			if got != want {
+				t.Errorf("NewToken() got = %v, want %v", newToken, want)
+			}
+		})
+
+	}
+	f("token with accountID and projectID", "1:2", "1:2")
+	f("max uint32 accountID", "4294967295:1", "4294967295:1")
+	f("max uint32 projectID", "1:4294967295", "1:4294967295")
+	f("max uint32 accountID and projectID", "4294967295:4294967295", "4294967295:4294967295")
+}
+
+func TestNewTokenFailure(t *testing.T) {
+	f := func(name string, token string) {
+		t.Helper()
+		t.Run(name, func(t *testing.T) {
+			newToken, err := NewToken(token)
+			if err == nil {
+				t.Fatalf("expecting non-nil error")
+			}
+			if newToken != nil {
+				t.Fatalf("expecting nil token")
+			}
+		})
+	}
+	f("empty token", "")
+	f("empty accountID and projectID", ":")
+	f("accountID and projectID not int values", "a:b")
+	f("missed projectID", "1:")
+	f("missed accountID", ":2")
+	f("large int value for accountID", "9223372036854775808:1")
+	f("large int value for projectID", "2:9223372036854775808")
+	f("both large int values incorrect", "9223372036854775809:9223372036854775808")
+	f("large uint32 values incorrect", "4294967297:4294967295")
+	f("negative accountID", "-100:100")
+	f("negative projectID", "100:-100")
+	f("negative accountID and projectID", "-100:-100")
+	f("accountID is string", "abcd:2")
+	f("projectID is string", "2:abcd")
+	f("empty many parts in the token", "::")
+	f("many string parts in the token", "a:b:c")
+	f("many int parts in the token", "1:2:3")
+}