diff --git a/programs/pkey/rsa_sign_pss.c b/programs/pkey/rsa_sign_pss.c
index 05fa1c4..9665dcf 100644
--- a/programs/pkey/rsa_sign_pss.c
+++ b/programs/pkey/rsa_sign_pss.c
@@ -36,6 +36,10 @@
 #include "polarssl/sha1.h"
 #include "polarssl/x509.h"
 
+#if defined _MSC_VER && !defined snprintf
+#define snprintf _snprintf
+#endif
+
 int main( int argc, char *argv[] )
 {
     FILE *f;
diff --git a/programs/pkey/rsa_verify_pss.c b/programs/pkey/rsa_verify_pss.c
index 1fb20d8..ce07707 100644
--- a/programs/pkey/rsa_verify_pss.c
+++ b/programs/pkey/rsa_verify_pss.c
@@ -36,6 +36,10 @@
 #include "polarssl/sha1.h"
 #include "polarssl/x509.h"
 
+#if defined _MSC_VER && !defined snprintf
+#define snprintf _snprintf
+#endif
+
 int main( int argc, char *argv[] )
 {
     FILE *f;