1 files changed, 6 insertions, 5 deletions
diff --git a/src/libzisp/value/rune.zig b/src/libzisp/value/rune.zig
index a6152b1..154ec13 100644
--- a/src/libzisp/value/rune.zig
+++ b/src/libzisp/value/rune.zig
@@ -22,11 +22,12 @@ pub fn isValidRune(s: []const u8) bool {
     if (s.len == 0 or s.len > 6) {
         return false;
     }
-    for (s) |c| {
-        switch (c) {
-            'A'...'Z' => {},
-            'a'...'z' => {},
-            else => return false,
+    if (!std.ascii.isAlphabetic(s[0])) {
+        return false;
+    }
+    for (s[1..]) |c| {
+        if (!std.ascii.isAlphanumeric(c)) {
+            return false;
         }
     }
     return true;