diff --git a/libnfc/log-printf.c b/libnfc/log-printf.c
index a157a56..0a6bfcd 100644
--- a/libnfc/log-printf.c
+++ b/libnfc/log-printf.c
@@ -56,7 +56,7 @@ log_fini (void)
 }
 
 void
-log_put (char *category, char *priority, char *format, ...)
+log_put (const char *category, const char *priority, const char *format, ...)
 {
   va_list va;
   va_start (va, format);
diff --git a/libnfc/log.h b/libnfc/log.h
index 879fbeb..40d3b2e 100644
--- a/libnfc/log.h
+++ b/libnfc/log.h
@@ -27,7 +27,7 @@
   #define LOGGING 1
   int	 log_init (void);
   int	 log_fini (void);
-  void log_put (char *category, char *priority, char *format, ...);
+  void log_put (const char *category, const char *priority, const char *format, ...);
   
   #define NFC_PRIORITY_FATAL  "fatal"
   #define NFC_PRIORITY_ALERT  "alert"