diff --git a/crates/test-programs/src/bin/p3_http_outbound_request_response_build.rs b/crates/test-programs/src/bin/p3_http_outbound_request_response_build.rs
index 0213986ad4d6..e041628f2e1d 100644
--- a/crates/test-programs/src/bin/p3_http_outbound_request_response_build.rs
+++ b/crates/test-programs/src/bin/p3_http_outbound_request_response_build.rs
@@ -54,6 +54,9 @@ impl test_programs::p3::exports::wasi::cli::run::Guest for Component {
             assert!(req.set_authority(Some("bad-port:99999")).is_err());
             assert!(req.set_authority(Some("bad-\nhost")).is_err());
             assert!(req.set_authority(Some("too-many-ports:80:80:80")).is_err());
+            // IPv6 addresses with and without a port should be allowed.
+            assert!(req.set_authority(Some("[::]:443")).is_ok());
+            assert!(req.set_authority(Some("[::]")).is_ok());
 
             assert!(
                 req.set_scheme(Some(&Scheme::Other("bad\nscheme".to_string())))
diff --git a/crates/wasi-http/src/p3/host/types.rs b/crates/wasi-http/src/p3/host/types.rs
index 252951688a0c..25af21312113 100644
--- a/crates/wasi-http/src/p3/host/types.rs
+++ b/crates/wasi-http/src/p3/host/types.rs
@@ -468,7 +468,10 @@ impl HostRequest for WasiHttpCtxView<'_> {
             req.authority = None;
             return Ok(Ok(()));
         };
-        let has_port = authority.contains(':');
+        let has_port = match authority.rsplit_once(']') {
+            Some((_, suffix)) => suffix.starts_with(':'),
+            None => authority.contains(':'),
+        };
         let Ok(authority) = http::uri::Authority::try_from(authority) else {
             return Ok(Err(()));
         };