diff --git a/SConstruct b/SConstruct
index e14102498..e3ded9680 100644
--- a/SConstruct
+++ b/SConstruct
@@ -833,7 +833,7 @@ class DXXProgram(DXXCommon):
 'editor/khelp.cpp',
 'editor/kmine.cpp',
 'editor/ksegmove.cpp',
-'editor/ksegsel.c',
+'editor/ksegsel.cpp',
 'editor/ksegsize.c',
 'editor/ktmap.c',
 'editor/kview.c',
diff --git a/similar/editor/ksegsel.c b/similar/editor/ksegsel.cpp
similarity index 99%
rename from similar/editor/ksegsel.c
rename to similar/editor/ksegsel.cpp
index a95761281..6b2b7a5d3 100644
--- a/similar/editor/ksegsel.c
+++ b/similar/editor/ksegsel.cpp
@@ -25,6 +25,7 @@ COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #include "editor/esegment.h"
 #include "editor/medmisc.h"
 #include "gameseg.h"
+#include "kdefs.h"
 
 // ---------------------------------------------------------------------------------------
 // Select previous segment.