diff --git a/Examples/test-suite/preproc.i b/Examples/test-suite/preproc.i
index 03789cb87..5ff263df7 100644
--- a/Examples/test-suite/preproc.i
+++ b/Examples/test-suite/preproc.i
@@ -1,5 +1,20 @@
 %module preproc
 
+/* check __cplusplus case */
+%header
+%{
+#ifdef __cplusplus
+extern "C"
+{
+#endif /* __cplusplus */
+  /* C code */
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+%}
+
+
 /* This interface file tests whether SWIG's extended C
    preprocessor is working right.