diff --git a/handlers/handlers.go b/handlers/handlers.go
index 0f2e066..5f2aba1 100644
--- a/handlers/handlers.go
+++ b/handlers/handlers.go
@@ -66,6 +66,11 @@ func (a *App) CreateShortURL(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "Invalid URL", http.StatusBadRequest)
 		return
 	}
+	// Verify alias is valid
+	if u.Alias != "" && !utils.IsValidAlias(u.Alias) {
+		http.Error(w, "Invalid Alias", http.StatusBadRequest)
+		return
+	}
 	// Check if URL entry already exists
 	existingURL := &URLEntry{}
 	a.DB.Where("url = ?", u.URL).Find(existingURL)
diff --git a/handlers/handlers_test.go b/handlers/handlers_test.go
index 2ba7e4b..dc5f84b 100644
--- a/handlers/handlers_test.go
+++ b/handlers/handlers_test.go
@@ -76,10 +76,13 @@ func TestInvalidCreate(t *testing.T) {
 		alias  string
 		status int
 	}{
-		"bad":      {url: "https/agoogle.com", alias: "ggls", status: http.StatusBadRequest},
-		"no colon": {url: "http//google.com", alias: "ggl", status: http.StatusBadRequest},
-		"empty":    {url: "", alias: "", status: http.StatusBadRequest},
-		"asdf":     {url: "asdf", alias: "", status: http.StatusBadRequest},
+		"bad":           {url: "https/agoogle.com", alias: "ggls", status: http.StatusBadRequest},
+		"no colon":      {url: "http//google.com", alias: "ggl", status: http.StatusBadRequest},
+		"empty":         {url: "", alias: "", status: http.StatusBadRequest},
+		"asdf":          {url: "asdf", alias: "", status: http.StatusBadRequest},
+		"spaces":        {url: "https://google.com", alias: "oh no spaces", status: http.StatusBadRequest},
+		"question mark": {url: "https://google.com", alias: "huh?", status: http.StatusBadRequest},
+		"percent":       {url: "https://google.com", alias: "test%20stuff", status: http.StatusBadRequest},
 	}
 
 	app := setup()
diff --git a/utils/utils.go b/utils/utils.go
index 94264fd..b8f0350 100644
--- a/utils/utils.go
+++ b/utils/utils.go
@@ -2,22 +2,23 @@ package utils
 
 import (
 	"math/rand"
-	"strings"
+	"regexp"
 	"time"
 )
 
-// Alphanumeric charset
-const CHARSET = "abcdefghijklmnopqrstuvwxyz" +
-	"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+const (
+	// Alphanumeric charset
+	CHARSET = "abcdefghijklmnopqrstuvwxyz" +
+		"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+
+	// RFC 3986 Section 2.3 URI Unreserved Characters
+	URIUnreservedChars = `^([A-Za-z0-9_.~-])+$`
+)
 
 // Tests whether a string is in the alphanumeric charset
-func IsAlphaNum(str string) bool {
-	for _, r := range []rune(str) {
-		if !strings.ContainsRune(CHARSET, r) {
-			return false
-		}
-	}
-	return true
+func IsValidAlias(str string) bool {
+	valid, err := regexp.MatchString(URIUnreservedChars, str)
+	return valid && err == nil
 }
 
 // Generate a random alphanumeric string of given length
diff --git a/utils/utils_test.go b/utils/utils_test.go
index 6ab095a..bc8b7f3 100644
--- a/utils/utils_test.go
+++ b/utils/utils_test.go
@@ -4,23 +4,31 @@ import (
 	"testing"
 )
 
-func TestIsAlphaNum(t *testing.T) {
+func TestValidAlias(t *testing.T) {
 	tests := map[string]struct {
 		name string
 		str  string
 		val  bool
 	}{
-		"basic":         {str: "hello", val: true},
-		"dash":          {str: "-", val: false},
-		"period":        {str: ".", val: false},
+		"LOWERCASE":     {str: "lowercase", val: true},
+		"UPPERCASE":     {str: "UPPERCASE", val: true},
+		"underscore":    {str: "_", val: true},
+		"period":        {str: ".", val: true},
+		"dash":          {str: "-", val: true},
+		"tilde":         {str: "~", val: true},
+		"adsf":          {str: "a_S-d.f~", val: true},
 		"question mark": {str: "?", val: false},
-		"backslash":     {str: "?", val: false},
+		"backslash":     {str: "\\", val: false},
+		"asterix":       {str: "*", val: false},
+		"ampersand":     {str: "&", val: false},
+		"space":         {str: " ", val: false},
+		"percent":       {str: "%", val: false},
 	}
 
 	for name, tc := range tests {
 		t.Run(name, func(t *testing.T) {
-			if IsAlphaNum(tc.str) != tc.val {
-				t.Errorf("For '%s', expected %t. Got %t instead.", tc.str, tc.val, IsAlphaNum(tc.str))
+			if IsValidAlias(tc.str) != tc.val {
+				t.Errorf("For '%s', expected %t. Got %t instead.", tc.str, tc.val, IsValidAlias(tc.str))
 			}
 		})
 	}
@@ -29,7 +37,7 @@ func TestIsAlphaNum(t *testing.T) {
 // For the code coverage why not
 func TestRandString(t *testing.T) {
 	str := RandString(6)
-	if len(str) == 6 && IsAlphaNum(str) {
+	if len(str) == 6 && IsValidAlias(str) {
 		return
 	}
 	t.Errorf("Seriously? How?")