diff --git a/src/support/lstrings.C b/src/support/lstrings.C
index 33a11b8386..ae5537a3b7 100644
--- a/src/support/lstrings.C
+++ b/src/support/lstrings.C
@@ -23,6 +23,7 @@
 #include "lstrings.h"
 #include "LRegex.h"
 #include "LAssert.h"
+#include "debug.h"
 
 using std::count;
 using std::transform;