diff --git a/programs/pkey/ecdsa.c b/programs/pkey/ecdsa.c
index 948066a..3cba7e8 100644
--- a/programs/pkey/ecdsa.c
+++ b/programs/pkey/ecdsa.c
@@ -60,7 +60,7 @@
 #else
 
 #if defined(VERBOSE)
-static void dump_buf( char *title, unsigned char *buf, size_t len )
+static void dump_buf( const char *title, unsigned char *buf, size_t len )
 {
     size_t i;
 
@@ -71,7 +71,7 @@
     printf( "\n" );
 }
 
-static void dump_pubkey( char *title, ecdsa_context *key )
+static void dump_pubkey( const char *title, ecdsa_context *key )
 {
     unsigned char buf[300];
     size_t len;