diff --git a/modules/libcom/src/osi/Makefile b/modules/libcom/src/osi/Makefile
index 10eb98be0..f0108e662 100644
--- a/modules/libcom/src/osi/Makefile
+++ b/modules/libcom/src/osi/Makefile
@@ -104,7 +104,7 @@ epicsReadline_INCLUDES += $(INCLUDES_$(COMMANDLINE_LIBRARY))
 
 Com_SRCS += epicsReadline.c
 
-Com_SRCS += epicsTempFile.cpp
+Com_SRCS += epicsTempFile.c
 Com_SRCS += epicsStdio.c
 Com_SRCS += osdStdio.c
 
diff --git a/modules/libcom/src/osi/os/WIN32/epicsTempFile.cpp b/modules/libcom/src/osi/os/WIN32/epicsTempFile.c
similarity index 99%
rename from modules/libcom/src/osi/os/WIN32/epicsTempFile.cpp
rename to modules/libcom/src/osi/os/WIN32/epicsTempFile.c
index 2283a8574..4d7bbf7dc 100644
--- a/modules/libcom/src/osi/os/WIN32/epicsTempFile.cpp
+++ b/modules/libcom/src/osi/os/WIN32/epicsTempFile.c
@@ -27,7 +27,6 @@
 // allow the teporary file directory to be set with the 
 // TMP environment varianble
 //
-extern "C"
 epicsShareFunc FILE * epicsShareAPI epicsTempFile ()
 {
     char * pName = _tempnam ( "c:\\tmp", "epics" );
diff --git a/modules/libcom/src/osi/os/posix/epicsTempFile.cpp b/modules/libcom/src/osi/os/posix/epicsTempFile.c
similarity index 98%
rename from modules/libcom/src/osi/os/posix/epicsTempFile.cpp
rename to modules/libcom/src/osi/os/posix/epicsTempFile.c
index c015f0418..6d7f631b2 100644
--- a/modules/libcom/src/osi/os/posix/epicsTempFile.cpp
+++ b/modules/libcom/src/osi/os/posix/epicsTempFile.c
@@ -13,7 +13,6 @@
 #define epicsExportSharedSymbols
 #include "epicsTempFile.h"
 
-extern "C"
 epicsShareFunc FILE * epicsShareAPI epicsTempFile ( void )
 {
     return tmpfile ();