diff --git a/tools/testing/memblock/linux/kernel.h b/tools/testing/memblock/linux/kernel.h
index c16d9cd2d1ae..4d1012d5be6e 100644
--- a/tools/testing/memblock/linux/kernel.h
+++ b/tools/testing/memblock/linux/kernel.h
@@ -9,5 +9,6 @@
 #include <linux/linkage.h>
 #include <linux/kconfig.h>
 #include <linux/string.h>
+#include <linux/ctype.h>
 
 #endif