diff --git a/examples/187-compile-error.sx b/examples/187-compile-error.sx
new file mode 100644
index 0000000..722bc12
--- /dev/null
+++ b/examples/187-compile-error.sx
@@ -0,0 +1,14 @@
+// `compile_error(msg)` raises a build-time diagnostic at the call
+// site. Used by builder fns (e.g. `#insert build_block_convert(...)`)
+// to reject malformed pack shapes with a clear message rather than
+// silently producing wrong code.
+//
+// The diagnostic appears at the source position of the
+// `compile_error` call. Argument must be a string literal — runtime
+// expressions can't be reported as compile errors.
+
+#import "modules/std.sx";
+
+#run compile_error("intentional compile error from #run");
+
+main :: () { }
diff --git a/tests/expected/187-compile-error.exit b/tests/expected/187-compile-error.exit
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/tests/expected/187-compile-error.exit
@@ -0,0 +1 @@
+1
diff --git a/tests/expected/187-compile-error.txt b/tests/expected/187-compile-error.txt
new file mode 100644
index 0000000..2082ca2
--- /dev/null
+++ b/tests/expected/187-compile-error.txt
@@ -0,0 +1 @@
+/Users/agra/projects/sx/examples/187-compile-error.sx:12:6: error: intentional compile error from #run