diff --git a/pgm.c b/pgm.c
index 7fcf706b..5d12d148 100644
--- a/pgm.c
+++ b/pgm.c
@@ -19,8 +19,9 @@
 
 /* $Id$ */
 
-#include <stdlib.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "pgm.h"
 
diff --git a/ppi.c b/ppi.c
index 7d93d874..fb9d1a6b 100644
--- a/ppi.c
+++ b/ppi.c
@@ -20,6 +20,7 @@
 /* $Id$ */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <fcntl.h>
 #include <unistd.h>
diff --git a/stk500.c b/stk500.c
index 07ac91f6..240fb9f5 100644
--- a/stk500.c
+++ b/stk500.c
@@ -29,6 +29,7 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <fcntl.h>
 #include <unistd.h>