diff --git a/tools/audio/samplebank.c b/tools/audio/samplebank.c
index 8eda227f27..30593e1d1e 100644
--- a/tools/audio/samplebank.c
+++ b/tools/audio/samplebank.c
@@ -7,6 +7,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 #include <assert.h>
+#include <stdlib.h>
 
 #include "xml.h"
 #include "samplebank.h"
diff --git a/tools/audio/samplebank_compiler.c b/tools/audio/samplebank_compiler.c
index c53515dc1f..f188654f62 100644
--- a/tools/audio/samplebank_compiler.c
+++ b/tools/audio/samplebank_compiler.c
@@ -8,6 +8,7 @@
  */
 #include <assert.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "xml.h"
diff --git a/tools/audio/soundfont_compiler.c b/tools/audio/soundfont_compiler.c
index 09a33a21f0..c8ba9633c6 100644
--- a/tools/audio/soundfont_compiler.c
+++ b/tools/audio/soundfont_compiler.c
@@ -12,6 +12,7 @@
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "xml.h"
diff --git a/tools/audio/xml.c b/tools/audio/xml.c
index 3df2c60a80..41f07a6454 100644
--- a/tools/audio/xml.c
+++ b/tools/audio/xml.c
@@ -10,6 +10,7 @@
 #include <ctype.h>
 #include <stdbool.h>
 #include <stdint.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "xml.h"