diff --git a/src/datetime.zig b/src/datetime.zig
index 04f1a6d5..3b9d5951 100644
--- a/src/datetime.zig
+++ b/src/datetime.zig
@@ -335,7 +335,7 @@ pub const DateTime = struct {
         }
         const tm = try parser.time(false);
 
-        if (parser.consumeIf(' ') == false) {
+        if (parser.unconsumed() == 0 or parser.consumeIf(' ') == false) {
             return error.InvalidTime;
         }
 
@@ -1496,6 +1496,9 @@ test "DateTime: parse RFC822" {
     try testing.expectError(error.InvalidTime, DateTime.parse("Wed, 01 Jan 20 20:1a:22 X", .rfc822));
     try testing.expectError(error.InvalidTime, DateTime.parse("Wed, 01 Jan 20 20:1a:22 ZZ", .rfc822));
 
+    // Missing timezone - input ends exactly at time boundary (was causing index out of bounds)
+    try testing.expectError(error.InvalidTime, DateTime.parse("Wed, 01 Jan 2020 10:10:10", .rfc822));
+
     {
         const dt = try DateTime.parse("31 Dec 68 23:59 Z", .rfc822);
         try testing.expectEqual(3124223940000000, dt.micros);