diff --git a/libsubid/api.c b/libsubid/api.c
index a7b904d0..a51b4e01 100644
--- a/libsubid/api.c
+++ b/libsubid/api.c
@@ -39,8 +39,8 @@
 #include "idmapping.h"
 #include "subid.h"
 
-const char *Prog = "(libsubid)";
-FILE *shadow_logfd;
+static const char *Prog = "(libsubid)";
+static FILE *shadow_logfd;
 
 bool libsubid_init(const char *progname, FILE * logfd)
 {