diff --git a/tests/extcmake_fetchcontent_tinytiff_test/extcmake_fetchcontent_tinytiff_test.cpp b/tests/extcmake_fetchcontent_tinytiff_test/extcmake_fetchcontent_tinytiff_test.cpp
index a76acc7..3e2fb13 100644
--- a/tests/extcmake_fetchcontent_tinytiff_test/extcmake_fetchcontent_tinytiff_test.cpp
+++ b/tests/extcmake_fetchcontent_tinytiff_test/extcmake_fetchcontent_tinytiff_test.cpp
@@ -1,4 +1,5 @@
 #include "tinytiffwriter.h"
+#include <stdlib.h>
 
 using namespace std;
 
diff --git a/tests/extcmake_tinytiff_test/extcmake_tinytiff_test.cpp b/tests/extcmake_tinytiff_test/extcmake_tinytiff_test.cpp
index a76acc7..3e2fb13 100644
--- a/tests/extcmake_tinytiff_test/extcmake_tinytiff_test.cpp
+++ b/tests/extcmake_tinytiff_test/extcmake_tinytiff_test.cpp
@@ -1,4 +1,5 @@
 #include "tinytiffwriter.h"
+#include <stdlib.h>
 
 using namespace std;
 
diff --git a/tests/tinytiffwriter_test/tinytiffwriter_test.cpp b/tests/tinytiffwriter_test/tinytiffwriter_test.cpp
index 959dcbc..f610327 100644
--- a/tests/tinytiffwriter_test/tinytiffwriter_test.cpp
+++ b/tests/tinytiffwriter_test/tinytiffwriter_test.cpp
@@ -3,6 +3,7 @@
 #include "test_results.h"
 #include "testimage_tools.h"
 #include <fstream>
+#include <string.h>
 #include <array>
 #ifdef TINYTIFF_TEST_LIBTIFF
 #include <tiffio.h>