diff --git a/modules/ar/src/panda3d-simulator/vpPanda3DPostProcessFilter.cpp b/modules/ar/src/panda3d-simulator/vpPanda3DPostProcessFilter.cpp
index 0a123b51f5..cecd919ed0 100644
--- a/modules/ar/src/panda3d-simulator/vpPanda3DPostProcessFilter.cpp
+++ b/modules/ar/src/panda3d-simulator/vpPanda3DPostProcessFilter.cpp
@@ -35,19 +35,18 @@
 #include <lightRampAttrib.h>
 
 BEGIN_VISP_NAMESPACE
-const char *vpPanda3DPostProcessFilter::FILTER_VERTEX_SHADER = R"shader(
-#version 330
-in vec4 p3d_Vertex;
-uniform mat4 p3d_ModelViewProjectionMatrix;
-in vec2 p3d_MultiTexCoord0;
-out vec2 texcoords;
-
-void main()
-{
-  gl_Position = p3d_ModelViewProjectionMatrix * p3d_Vertex;
-  texcoords = p3d_MultiTexCoord0;
-}
-)shader";
+const std::string vpPanda3DPostProcessFilter::FILTER_VERTEX_SHADER =
+"#version 330\n"
+"in vec4 p3d_Vertex;\n"
+"uniform mat4 p3d_ModelViewProjectionMatrix;\n"
+"in vec2 p3d_MultiTexCoord0;\n"
+"out vec2 texcoords;\n"
+
+"void main()\n"
+"{\n"
+"  gl_Position = p3d_ModelViewProjectionMatrix * p3d_Vertex;\n"
+"  texcoords = p3d_MultiTexCoord0;\n"
+"}\n";
 
 void vpPanda3DPostProcessFilter::setupScene()
 {