diff --git a/src/plugins/debugger/cdb/bytearrayinputstream.cpp b/src/plugins/debugger/cdb/bytearrayinputstream.cpp
index c7df38e8350..2ac8545facc 100644
--- a/src/plugins/debugger/cdb/bytearrayinputstream.cpp
+++ b/src/plugins/debugger/cdb/bytearrayinputstream.cpp
@@ -33,6 +33,8 @@
 
 #include "bytearrayinputstream.h"
 
+#include <ctype.h>
+
 namespace Debugger {
 namespace Internal {