diff --git a/formatter.h b/formatter.h
index c2e9c0f..ea5e711 100644
--- a/formatter.h
+++ b/formatter.h
@@ -1,6 +1,7 @@
 #ifndef FORMATTER_H
 #define FORMATTER_H
 
+#include <cstdlib>
 #include <node.h>
 #include <node_buffer.h>
 #include "macros.h"
@@ -85,4 +86,4 @@ class Formatter : public ObjectWrap {
 
 }
 
-#endif
\ No newline at end of file
+#endif
diff --git a/mixer.h b/mixer.h
index 1b2fa4a..83683b9 100644
--- a/mixer.h
+++ b/mixer.h
@@ -1,6 +1,7 @@
 #ifndef MIXER_H
 #define MIXER_H
 
+#include <cstdlib>
 #include <node.h>
 #include <node_buffer.h>
 #include "macros.h"
@@ -100,4 +101,4 @@ class Mixer : public ObjectWrap {
 
 }
 
-#endif
\ No newline at end of file
+#endif
diff --git a/unzipper.h b/unzipper.h
index dfb13ee..f847782 100644
--- a/unzipper.h
+++ b/unzipper.h
@@ -1,6 +1,8 @@
 #ifndef UNZIPPER_H
 #define UNZIPPER_H
 
+#include <cstdlib>
+#include <cstring>
 #include <node.h>
 #include <node_buffer.h>
 #include "macros.h"
@@ -96,4 +98,4 @@ class Unzipper : public ObjectWrap {
 
 }
 
-#endif
\ No newline at end of file
+#endif
diff --git a/zipper.h b/zipper.h
index e79315f..cfcdc1c 100644
--- a/zipper.h
+++ b/zipper.h
@@ -1,6 +1,8 @@
 #ifndef ZIPPER_H
 #define ZIPPER_H
 
+#include <cstdlib>
+#include <cstring>
 #include <node.h>
 #include <node_buffer.h>
 #include "macros.h"
@@ -103,4 +105,4 @@ class Zipper : public ObjectWrap {
 
 }
 
-#endif
\ No newline at end of file
+#endif