diff --git a/toonz/sources/include/tools/assistants/guidelineellipse.h b/toonz/sources/include/tools/assistants/guidelineellipse.h
new file mode 100644
index 0000000..c8b1607
--- /dev/null
+++ b/toonz/sources/include/tools/assistants/guidelineellipse.h
@@ -0,0 +1,55 @@
+#pragma once
+
+#ifndef GUIDELINEELLIPSE_INCLUDED
+#define GUIDELINEELLIPSE_INCLUDED
+
+// TnzTools includes
+#include <tools/assistant.h>
+
+
+#undef DVAPI
+#undef DVVAR
+#ifdef TNZTOOLS_EXPORTS
+#define DVAPI DV_EXPORT_API
+#define DVVAR DV_EXPORT_VAR
+#else
+#define DVAPI DV_IMPORT_API
+#define DVVAR DV_IMPORT_VAR
+#endif
+
+
+//==============================================================
+
+//*****************************************************************************************
+//    TGuidelineEllipse definition
+//*****************************************************************************************
+
+class DVAPI TGuidelineEllipse : public TGuideline {
+public:
+  const TAffine matrix;
+  const TAffine matrixInv;
+
+  TGuidelineEllipse(
+    bool enabled,
+    double magnetism,
+    TAffine matrix );
+
+  TGuidelineEllipse(
+    bool enabled,
+    double magnetism,
+    TAffine matrix,
+    TAffine matrixInv );
+
+  //! returns false when ellipse is invisible
+  static bool truncateEllipse(
+    TAngleRangeSet &ranges,
+    const TAffine &ellipseMatrixInv,
+    const TRectD &bounds );
+
+  static int calcSegmentsCount(const TAffine &ellipseMatrix, double pixelSize);
+
+  TTrackPoint transformPoint(const TTrackPoint &point) const override;
+  void draw(bool active, bool enabled) const override;
+};
+
+#endif
diff --git a/toonz/sources/include/tools/assistants/guidelineline.h b/toonz/sources/include/tools/assistants/guidelineline.h
new file mode 100644
index 0000000..7373be9
--- /dev/null
+++ b/toonz/sources/include/tools/assistants/guidelineline.h
@@ -0,0 +1,83 @@
+#pragma once
+
+#ifndef GUIDELINELINE_INCLUDED
+#define GUIDELINELINE_INCLUDED
+
+// TnzTools includes
+#include <tools/assistant.h>
+
+
+#undef DVAPI
+#undef DVVAR
+#ifdef TNZTOOLS_EXPORTS
+#define DVAPI DV_EXPORT_API
+#define DVVAR DV_EXPORT_VAR
+#else
+#define DVAPI DV_IMPORT_API
+#define DVVAR DV_IMPORT_VAR
+#endif
+
+
+//==============================================================
+
+//*****************************************************************************************
+//    TGuidelineLineBase definition
+//*****************************************************************************************
+
+class DVAPI TGuidelineLineBase : public TGuideline {
+public:
+  const TPointD p0;
+  const TPointD p1;
+
+  TGuidelineLineBase(bool enabled, double magnetism, const TPointD &p0, const TPointD &p1);
+  void drawLine(const TPointD &p0, const TPointD &p1, bool restrict0, bool restrict1, bool active, bool enabled) const;
+  static TPointD calcDirection(const TPointD &p0, const TPointD &p1);
+  static bool truncateInfiniteLine(const TRectD &bounds, TPointD &p0, TPointD &p1);
+  static bool truncateRay(const TRectD &bounds, TPointD &p0, TPointD &p1);
+  static bool truncateLine(const TRectD &bounds, TPointD &p0, TPointD &p1);
+};
+
+
+//*****************************************************************************************
+//    TGuidelineLine definition
+//*****************************************************************************************
+
+class DVAPI TGuidelineLine : public TGuidelineLineBase {
+public:
+  const TPointD dir;
+  const double dist;
+
+  TGuidelineLine(bool enabled, double magnetism, const TPointD &p0, const TPointD &p1);
+  TTrackPoint transformPoint(const TTrackPoint &point) const override;
+  void draw(bool active, bool enabled) const override;
+};
+
+
+//*****************************************************************************************
+//    TGuidelineInfiniteLine definition
+//*****************************************************************************************
+
+class DVAPI TGuidelineInfiniteLine : public TGuidelineLineBase {
+public:
+  const TPointD dir;
+
+  TGuidelineInfiniteLine(bool enabled, double magnetism, const TPointD &p0, const TPointD &p1);
+  TTrackPoint transformPoint(const TTrackPoint &point) const override;
+  void draw(bool active, bool enabled) const override;
+};
+
+
+//*****************************************************************************************
+//    TGuidelineRay definition
+//*****************************************************************************************
+
+class DVAPI TGuidelineRay : public TGuidelineLineBase {
+public:
+  const TPointD dir;
+
+  TGuidelineRay(bool enabled, double magnetism, const TPointD &p0, const TPointD &p1);
+  TTrackPoint transformPoint(const TTrackPoint &point) const override;
+  void draw(bool active, bool enabled) const override;
+};
+
+#endif
diff --git a/toonz/sources/tnztools/CMakeLists.txt b/toonz/sources/tnztools/CMakeLists.txt
index 51f2e70..101eb4e 100644
--- a/toonz/sources/tnztools/CMakeLists.txt
+++ b/toonz/sources/tnztools/CMakeLists.txt
@@ -55,8 +55,8 @@ set(HEADERS
     ../include/tools/modifiers/modifiertest.h
     ../include/tools/modifiers/modifiersegmentation.h
     ../include/tools/modifiers/modifierassistants.h
-    assistants/guidelineline.h
-    assistants/guidelineellipse.h
+    ../include/tools/assistants/guidelineline.h
+    ../include/tools/assistants/guidelineellipse.h
 )
 
 set(SOURCES
diff --git a/toonz/sources/tnztools/assistants/assistantellipse.cpp b/toonz/sources/tnztools/assistants/assistantellipse.cpp
index 1a8666f..9a2c5c0 100644
--- a/toonz/sources/tnztools/assistants/assistantellipse.cpp
+++ b/toonz/sources/tnztools/assistants/assistantellipse.cpp
@@ -1,10 +1,9 @@
 
 
-#include "guidelineline.h"
-#include "guidelineellipse.h"
-
 // TnzTools includes
 #include <tools/assistant.h>
+#include <tools/assistants/guidelineline.h>
+#include <tools/assistants/guidelineellipse.h>
 
 // TnzCore includes
 #include <tgl.h>
diff --git a/toonz/sources/tnztools/assistants/assistantline.cpp b/toonz/sources/tnztools/assistants/assistantline.cpp
index 01aaaa7..ff2a9b4 100644
--- a/toonz/sources/tnztools/assistants/assistantline.cpp
+++ b/toonz/sources/tnztools/assistants/assistantline.cpp
@@ -1,9 +1,9 @@
 
 
-#include "guidelineline.h"
-
 // TnzTools includes
 #include <tools/assistant.h>
+#include <tools/assistants/guidelineline.h>
+
 
 // TnzCore includes
 #include <tgl.h>
diff --git a/toonz/sources/tnztools/assistants/assistantvanishingpoint.cpp b/toonz/sources/tnztools/assistants/assistantvanishingpoint.cpp
index 163e3ab..94867e0 100644
--- a/toonz/sources/tnztools/assistants/assistantvanishingpoint.cpp
+++ b/toonz/sources/tnztools/assistants/assistantvanishingpoint.cpp
@@ -1,9 +1,8 @@
 
 
-#include "guidelineline.h"
-
 // TnzTools includes
 #include <tools/assistant.h>
+#include <tools/assistants/guidelineline.h>
 
 // TnzCore includes
 #include <tgl.h>
diff --git a/toonz/sources/tnztools/assistants/guidelineellipse.cpp b/toonz/sources/tnztools/assistants/guidelineellipse.cpp
index 068a68b..51014c2 100644
--- a/toonz/sources/tnztools/assistants/guidelineellipse.cpp
+++ b/toonz/sources/tnztools/assistants/guidelineellipse.cpp
@@ -1,6 +1,6 @@
 
 
-#include "guidelineellipse.h"
+#include <tools/assistants/guidelineellipse.h>
 
 // TnzCore includes
 #include "tgl.h"
diff --git a/toonz/sources/tnztools/assistants/guidelineellipse.h b/toonz/sources/tnztools/assistants/guidelineellipse.h
deleted file mode 100644
index c8b1607..0000000
--- a/toonz/sources/tnztools/assistants/guidelineellipse.h
+++ /dev/null
@@ -1,55 +0,0 @@
-#pragma once
-
-#ifndef GUIDELINEELLIPSE_INCLUDED
-#define GUIDELINEELLIPSE_INCLUDED
-
-// TnzTools includes
-#include <tools/assistant.h>
-
-
-#undef DVAPI
-#undef DVVAR
-#ifdef TNZTOOLS_EXPORTS
-#define DVAPI DV_EXPORT_API
-#define DVVAR DV_EXPORT_VAR
-#else
-#define DVAPI DV_IMPORT_API
-#define DVVAR DV_IMPORT_VAR
-#endif
-
-
-//==============================================================
-
-//*****************************************************************************************
-//    TGuidelineEllipse definition
-//*****************************************************************************************
-
-class DVAPI TGuidelineEllipse : public TGuideline {
-public:
-  const TAffine matrix;
-  const TAffine matrixInv;
-
-  TGuidelineEllipse(
-    bool enabled,
-    double magnetism,
-    TAffine matrix );
-
-  TGuidelineEllipse(
-    bool enabled,
-    double magnetism,
-    TAffine matrix,
-    TAffine matrixInv );
-
-  //! returns false when ellipse is invisible
-  static bool truncateEllipse(
-    TAngleRangeSet &ranges,
-    const TAffine &ellipseMatrixInv,
-    const TRectD &bounds );
-
-  static int calcSegmentsCount(const TAffine &ellipseMatrix, double pixelSize);
-
-  TTrackPoint transformPoint(const TTrackPoint &point) const override;
-  void draw(bool active, bool enabled) const override;
-};
-
-#endif
diff --git a/toonz/sources/tnztools/assistants/guidelineline.cpp b/toonz/sources/tnztools/assistants/guidelineline.cpp
index e3f3b50..9018ccb 100644
--- a/toonz/sources/tnztools/assistants/guidelineline.cpp
+++ b/toonz/sources/tnztools/assistants/guidelineline.cpp
@@ -1,6 +1,6 @@
 
 
-#include "guidelineline.h"
+#include <tools/assistants/guidelineline.h>
 
 // TnzCore includes
 #include "tgl.h"
diff --git a/toonz/sources/tnztools/assistants/guidelineline.h b/toonz/sources/tnztools/assistants/guidelineline.h
deleted file mode 100644
index 7373be9..0000000
--- a/toonz/sources/tnztools/assistants/guidelineline.h
+++ /dev/null
@@ -1,83 +0,0 @@
-#pragma once
-
-#ifndef GUIDELINELINE_INCLUDED
-#define GUIDELINELINE_INCLUDED
-
-// TnzTools includes
-#include <tools/assistant.h>
-
-
-#undef DVAPI
-#undef DVVAR
-#ifdef TNZTOOLS_EXPORTS
-#define DVAPI DV_EXPORT_API
-#define DVVAR DV_EXPORT_VAR
-#else
-#define DVAPI DV_IMPORT_API
-#define DVVAR DV_IMPORT_VAR
-#endif
-
-
-//==============================================================
-
-//*****************************************************************************************
-//    TGuidelineLineBase definition
-//*****************************************************************************************
-
-class DVAPI TGuidelineLineBase : public TGuideline {
-public:
-  const TPointD p0;
-  const TPointD p1;
-
-  TGuidelineLineBase(bool enabled, double magnetism, const TPointD &p0, const TPointD &p1);
-  void drawLine(const TPointD &p0, const TPointD &p1, bool restrict0, bool restrict1, bool active, bool enabled) const;
-  static TPointD calcDirection(const TPointD &p0, const TPointD &p1);
-  static bool truncateInfiniteLine(const TRectD &bounds, TPointD &p0, TPointD &p1);
-  static bool truncateRay(const TRectD &bounds, TPointD &p0, TPointD &p1);
-  static bool truncateLine(const TRectD &bounds, TPointD &p0, TPointD &p1);
-};
-
-
-//*****************************************************************************************
-//    TGuidelineLine definition
-//*****************************************************************************************
-
-class DVAPI TGuidelineLine : public TGuidelineLineBase {
-public:
-  const TPointD dir;
-  const double dist;
-
-  TGuidelineLine(bool enabled, double magnetism, const TPointD &p0, const TPointD &p1);
-  TTrackPoint transformPoint(const TTrackPoint &point) const override;
-  void draw(bool active, bool enabled) const override;
-};
-
-
-//*****************************************************************************************
-//    TGuidelineInfiniteLine definition
-//*****************************************************************************************
-
-class DVAPI TGuidelineInfiniteLine : public TGuidelineLineBase {
-public:
-  const TPointD dir;
-
-  TGuidelineInfiniteLine(bool enabled, double magnetism, const TPointD &p0, const TPointD &p1);
-  TTrackPoint transformPoint(const TTrackPoint &point) const override;
-  void draw(bool active, bool enabled) const override;
-};
-
-
-//*****************************************************************************************
-//    TGuidelineRay definition
-//*****************************************************************************************
-
-class DVAPI TGuidelineRay : public TGuidelineLineBase {
-public:
-  const TPointD dir;
-
-  TGuidelineRay(bool enabled, double magnetism, const TPointD &p0, const TPointD &p1);
-  TTrackPoint transformPoint(const TTrackPoint &point) const override;
-  void draw(bool active, bool enabled) const override;
-};
-
-#endif