diff --git a/libraries/timidityplus/freq.cpp b/libraries/timidityplus/freq.cpp
index e4c50a6c64..670b43ea22 100644
--- a/libraries/timidityplus/freq.cpp
+++ b/libraries/timidityplus/freq.cpp
@@ -20,6 +20,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <math.h>
 #include "timidity.h"
 #include "common.h"
diff --git a/libraries/timidityplus/quantity.cpp b/libraries/timidityplus/quantity.cpp
index ea814006cd..a6628a2fc3 100644
--- a/libraries/timidityplus/quantity.cpp
+++ b/libraries/timidityplus/quantity.cpp
@@ -24,6 +24,7 @@
 */
 
 #include <stdlib.h>
+#include <string.h>
 #include <math.h>
 
 #include "timidity.h"
diff --git a/libraries/timidityplus/resample.cpp b/libraries/timidityplus/resample.cpp
index 9df494344b..5638dec07a 100644
--- a/libraries/timidityplus/resample.cpp
+++ b/libraries/timidityplus/resample.cpp
@@ -23,6 +23,7 @@
 #include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include "timidity.h"
 #include "common.h"