diff --git a/modules/math.js b/modules/math.js
index b3bbfcb..4add6a1 100644
--- a/modules/math.js
+++ b/modules/math.js
@@ -170,10 +170,10 @@ function modsqrt(n, modulus) {
 
 	if (n % modulus === 0n) {
 		return 0n;
-	} else if (legendreSymbol(n, modulus) !== 1n) {
-		throw new Error("radicand is not a quadratic residue of the modulus");
 	} else if (modulus === 2n) {
 		return n % 2n;
+	} else if (legendreSymbol(n, modulus) !== 1n) {
+		throw new Error("radicand is not a quadratic residue of the modulus");
 	} else if (modulus % 4n === 3n) {
 		return modpow(n, (modulus+1n)/4n, modulus);
 	}