diff --git a/examples/pn53x-sam.c b/examples/pn53x-sam.c
index ee9d664..6bbf8bc 100644
--- a/examples/pn53x-sam.c
+++ b/examples/pn53x-sam.c
@@ -52,7 +52,7 @@
 #define TIMEOUT 60              // secs.
 
 void
-wait_one_minute ()
+wait_one_minute (void)
 {
   int     secs = 0;
 
diff --git a/utils/nfc-mfclassic.c b/utils/nfc-mfclassic.c
index c3d7d95..5c58149 100644
--- a/utils/nfc-mfclassic.c
+++ b/utils/nfc-mfclassic.c
@@ -214,7 +214,7 @@ authenticate (uint32_t uiBlock)
 }
 
 static bool
-unlock_card()
+unlock_card (void)
 {
   printf ("Unlocking card\n");