diff --git a/toonz/sources/common/tvrender/tflash.cpp b/toonz/sources/common/tvrender/tflash.cpp
index d4ed7a8e..bb5d752d 100644
--- a/toonz/sources/common/tvrender/tflash.cpp
+++ b/toonz/sources/common/tvrender/tflash.cpp
@@ -221,6 +221,19 @@ void computeOutlineBoundary(vector<TStroke *> &outlines, list<FlashPolyline> &po
 
 //-------------------------------------------------------------------
 
+//	TFlash::drawSegments and TFlash::drawquads cannot be inline defined
+//	since size of TSegment and TQuadratic are unkown in the header
+
+void TFlash::drawSegments(const vector<TSegment> segmentArray, bool isGradientColor)
+{
+}
+
+void TFlash::drawquads(const vector<TQuadratic> quadsArray)
+{
+}
+
+//-------------------------------------------------------------------
+
 bool PolyStyle::operator==(const PolyStyle &p) const
 {
 	if (m_type != p.m_type)
diff --git a/toonz/sources/include/tflash.h b/toonz/sources/include/tflash.h
index 74ff81fa..d4cab616 100644
--- a/toonz/sources/include/tflash.h
+++ b/toonz/sources/include/tflash.h
@@ -78,8 +78,8 @@ public:
 	void drawRegion(const TRegion &r, int clippedShapes = 0) {}
 	void drawCenterline(const TStroke *s, bool drawAll) {}
 	bool drawOutline(TStroke *s) { return false; }
-	void drawSegments(const vector<TSegment> segmentArray, bool isGradientColor) {}
-	void drawquads(const vector<TQuadratic> quadsArray) {}
+	void drawSegments(const vector<TSegment> segmentArray, bool isGradientColor);
+	void drawquads(const vector<TQuadratic> quadsArray);
 	USHORT buildImage(const TImageP img, bool isMask) { return 0; }
 	void draw(const TImageP vi, const TColorFunction *cf) {}
 	void beginFrame(int frameIndex) {}