diff --git a/tests/tunit/tool1394.c b/tests/tunit/tool1394.c
index 5abb7ad525..94a1f62a79 100644
--- a/tests/tunit/tool1394.c
+++ b/tests/tunit/tool1394.c
@@ -23,6 +23,8 @@
  ***************************************************************************/
 #include "unitcheck.h"
 
+#include "curl_mem_undef.h" /* FIRST include file */
+
 #include "tool_getparam.h"
 
 #include "memdebug.h" /* LAST include file */
diff --git a/tests/tunit/tool1604.c b/tests/tunit/tool1604.c
index e50a074d96..ff172fbe71 100644
--- a/tests/tunit/tool1604.c
+++ b/tests/tunit/tool1604.c
@@ -23,6 +23,8 @@
  ***************************************************************************/
 #include "unitcheck.h"
 
+#include "curl_mem_undef.h" /* FIRST include file */
+
 #include "tool_cfgable.h"
 #include "tool_doswin.h"
 
diff --git a/tests/tunit/tool1621.c b/tests/tunit/tool1621.c
index 4919988c6c..0c1f58d396 100644
--- a/tests/tunit/tool1621.c
+++ b/tests/tunit/tool1621.c
@@ -23,6 +23,8 @@
  ***************************************************************************/
 #include "unitcheck.h"
 
+#include "curl_mem_undef.h" /* FIRST include file */
+
 #include "tool_xattr.h"
 
 #include "memdebug.h" /* LAST include file */