diff --git a/examples/simple/BUILD.bazel b/examples/simple/BUILD.bazel
index cc96ab34..ef89b555 100644
--- a/examples/simple/BUILD.bazel
+++ b/examples/simple/BUILD.bazel
@@ -13,6 +13,7 @@ ts_project(
     # "." is the same as default
     # explicitly given as a regression test for https://github.com/aspect-build/rules_ts/issues/195
     out_dir = ".",
+    visibility = ["//examples:__subpackages__"],
     # Note, the tsconfig attribute defaults to the tsconfig.json file in this directory.
     # tsconfig = "<default>",
     deps = [
diff --git a/examples/srcs/BUILD.bazel b/examples/srcs/BUILD.bazel
index a902f228..4e67fd3d 100644
--- a/examples/srcs/BUILD.bazel
+++ b/examples/srcs/BUILD.bazel
@@ -26,6 +26,39 @@ ts_project(
     out_dir = "filegroup",
 )
 
+ts_project(
+    name = "srcs-filegroup-gentsconfig",
+    srcs = [":srcs"],
+    tsconfig = {
+        "compilerOptions": {
+            "outDir": "filegroup-gentsconfig",
+        },
+    },
+)
+
+ts_project(
+    name = "srcs-filegroup-sibling",
+    srcs = [
+        ":srcs",
+        "//examples/simple:ts",
+    ],
+    out_dir = "filegroup-sibling",
+)
+
+ts_project(
+    name = "srcs-filegroup-sibling-gentsconfig",
+    srcs = [
+        ":srcs",
+        "//examples/simple:ts",
+    ],
+    tsconfig = {
+        "compilerOptions": {
+            "allowJs": True,
+            "outDir": "filegroup-sibling-gentsconfig",
+        },
+    },
+)
+
 # Tools can also generate .ts source files, so the sources are actually in the bazel-out tree.
 # This example just writes one directly but this could instead be some tool.
 write_file(
@@ -47,6 +80,20 @@ ts_project(
     out_dir = "generated",
 )
 
+ts_project(
+    name = "srcs-generated-gentsconfig",
+    # Demonstrates that you can mix sources with generated files
+    srcs = [
+        "a.ts",
+        "generated.ts",
+    ],
+    tsconfig = {
+        "compilerOptions": {
+            "outDir": "generated-gentsconfig",
+        },
+    },
+)
+
 # Testing what outputs are actually produced
 [
     params_file(
@@ -58,7 +105,11 @@ ts_project(
     for case in [
         "auto",
         "filegroup",
+        "filegroup-gentsconfig",
+        "filegroup-sibling",
+        "filegroup-sibling-gentsconfig",
         "generated",
+        "generated-gentsconfig",
     ]
 ]
 
@@ -71,7 +122,11 @@ ts_project(
     for case in [
         "auto",
         "filegroup",
+        "filegroup-gentsconfig",
+        "filegroup-sibling",
+        "filegroup-sibling-gentsconfig",
         "generated",
+        "generated-gentsconfig",
     ]
 ]
 
diff --git a/ts/private/ts_project.bzl b/ts/private/ts_project.bzl
index 367bba07..cd50d879 100644
--- a/ts/private/ts_project.bzl
+++ b/ts/private/ts_project.bzl
@@ -79,6 +79,11 @@ def _ts_project_impl(ctx):
 
     validation_outs = []
     if ctx.attr.validate:
+        package_slash = ctx.label.package + "/"
+        for src in srcs_inputs:
+            if not src.path.startswith(package_slash):
+                fail("ts_project(%s) src (%s) must be in the same package" % (ctx.label, src.path))
+
         validation_outs.extend(_validate_lib.validation_action(ctx, tsconfig_inputs))
         _lib.validate_tsconfig_dirs(ctx.attr.root_dir, ctx.attr.out_dir, typings_out_dir)