diff --git a/src/libCom/osi/os/default/osdEnv.c b/src/libCom/osi/os/default/osdEnv.c
index 27cb1efd2..d069f4639 100644
--- a/src/libCom/osi/os/default/osdEnv.c
+++ b/src/libCom/osi/os/default/osdEnv.c
@@ -64,7 +64,7 @@ epicsShareFunc void epicsShareAPI epicsEnvUnset (const char *name)
 {
     iocshEnvClear(name);
     if (getenv(name) != NULL)
-        putenv(name);
+        putenv((char*)name);
 }
 
 /*