diff --git a/src/ca/caDiagnostics.h b/src/ca/caDiagnostics.h
index 52dffc4b3..c09c6bc0c 100644
--- a/src/ca/caDiagnostics.h
+++ b/src/ca/caDiagnostics.h
@@ -1,12 +1,21 @@
 
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 enum appendNumberFlag {appendNumber, dontAppendNumber};
-
 int catime ( char *channelName, unsigned channelCount, enum appendNumberFlag appNF );
 
 int acctst ( char *pname, unsigned channelCount, unsigned repititionCount );
 
-void caConnTest ( const char *pNameIn, unsigned channelCountIn, double delayIn );
-
 #define CATIME_OK 0
 #define CATIME_ERROR -1
 
+#ifdef __cplusplus
+}
+#endif
+
+void caConnTest ( const char *pNameIn, unsigned channelCountIn, double delayIn );
+
+