diff --git a/libbacktrace/UnwindMap.cpp b/libbacktrace/UnwindMap.cpp
index 1615518..4f9831b 100644
--- a/libbacktrace/UnwindMap.cpp
+++ b/libbacktrace/UnwindMap.cpp
@@ -15,6 +15,7 @@
  */
 
 #include <pthread.h>
+#include <stdlib.h>
 #include <sys/types.h>
 #include <unistd.h>