diff --git a/acsApp/src/devMCB4B.cc b/acsApp/src/devMCB4B.cc
index 8bf295a..77617b0 100644
--- a/acsApp/src/devMCB4B.cc
+++ b/acsApp/src/devMCB4B.cc
@@ -66,7 +66,7 @@ struct motor_dset devMCB4B =
     MCB4B_end_trans
 };
 
-epicsExportAddress(dset,devMCB4B);
+extern "C" {epicsExportAddress(dset,devMCB4B);}
 
 
 /* --------------------------- program data --------------------- */
diff --git a/acsApp/src/drvMCB4B.cc b/acsApp/src/drvMCB4B.cc
index b6442cf..8354bfc 100644
--- a/acsApp/src/drvMCB4B.cc
+++ b/acsApp/src/drvMCB4B.cc
@@ -110,7 +110,7 @@ struct
 #endif
 } drvMCB4B = {2, report, init};
 
-epicsExportAddress(drvet, drvMCB4B);
+extern "C" {epicsExportAddress(drvet, drvMCB4B);}
 
 STATIC struct thread_args targs = {SCAN_RATE, &MCB4B_access};