diff --git a/benchmark.c b/benchmark.c
index dd06abb..21976a1 100644
--- a/benchmark.c
+++ b/benchmark.c
@@ -45,7 +45,8 @@ static volatile bool finished = false;
 
 /** interruptBench is used to stop the current benchmark */
 static void
-interruptBench() {
+interruptBench(int signo) {
+  (void)signo;
   finished = true;
 }
 
diff --git a/main.c b/main.c
index f8026bf..8b8644d 100644
--- a/main.c
+++ b/main.c
@@ -43,7 +43,8 @@
 
 /** alarmInterrupt is used to print out the progress at specific intervals */
 static void
-alarmInterrupt() {
+alarmInterrupt(int signo) {
+  (void)signo;
   if(!printProgress())
     alarm(PRINTERVAL);
 }
diff --git a/md5.c b/md5.c
index 5d3562f..0070220 100644
--- a/md5.c
+++ b/md5.c
@@ -47,7 +47,7 @@
 #define CC 0x98badcfe
 #define DD 0x10325476
 
-static void (*md5_50_variant)();
+static void (*md5_50_variant)(uint8_t *msg, const unsigned int msgLen);
 static void md5_50f(uint8_t *msg, const unsigned int msgLen);
 static void md5_50s(uint8_t *msg, const unsigned int msgLen);