diff --git a/plugins/GSdx/GSDeviceOGL.cpp b/plugins/GSdx/GSDeviceOGL.cpp
index 92c842789c..132836d4e5 100644
--- a/plugins/GSdx/GSDeviceOGL.cpp
+++ b/plugins/GSdx/GSDeviceOGL.cpp
@@ -206,7 +206,9 @@ bool GSDeviceOGL::Create(GSWnd* wnd)
 		{2 , GL_UNSIGNED_SHORT , GL_FALSE , sizeof(GSVertex)    , (const GLvoid*)(16) } ,
 		{1 , GL_UNSIGNED_INT   , GL_FALSE , sizeof(GSVertex)    , (const GLvoid*)(20) } ,
 		{2 , GL_UNSIGNED_SHORT , GL_FALSE , sizeof(GSVertex)    , (const GLvoid*)(24) } ,
+		// FIXME only first byte is useful
 		{4 , GL_UNSIGNED_BYTE  , GL_TRUE  , sizeof(GSVertex)    , (const GLvoid*)(28) } ,
+		// TEST ME {1 , GL_UNSIGNED_BYTE  , GL_TRUE  , sizeof(GSVertex)    , (const GLvoid*)(28) } ,
 	};
 	m_va = new GSVertexBufferStateOGL(sizeof(GSVertexPT1), il_convert, countof(il_convert));
 
diff --git a/plugins/GSdx/res/glsl/tfx_vgs.glsl b/plugins/GSdx/res/glsl/tfx_vgs.glsl
index 94bd783f44..7f98d3de1c 100644
--- a/plugins/GSdx/res/glsl/tfx_vgs.glsl
+++ b/plugins/GSdx/res/glsl/tfx_vgs.glsl
@@ -14,6 +14,8 @@ layout(location = 3) in float i_q;
 layout(location = 4) in uvec2 i_p;
 layout(location = 5) in uint  i_z;
 layout(location = 6) in uvec2 i_uv;
+// FIXME only first byte is useful
+//TEST_ME layout(location = 7) in float i_f;
 layout(location = 7) in vec4  i_f;
 
 out SHADER
diff --git a/plugins/GSdx/res/glsl_source.h b/plugins/GSdx/res/glsl_source.h
index 72f1bccb22..3388ebf911 100644
--- a/plugins/GSdx/res/glsl_source.h
+++ b/plugins/GSdx/res/glsl_source.h
@@ -465,6 +465,8 @@ static const char* tfx_vgs_glsl =
 	"layout(location = 4) in uvec2 i_p;\n"
 	"layout(location = 5) in uint  i_z;\n"
 	"layout(location = 6) in uvec2 i_uv;\n"
+	"// FIXME only first byte is useful\n"
+	"//TEST_ME layout(location = 7) in float i_f;\n"
 	"layout(location = 7) in vec4  i_f;\n"
 	"\n"
 	"out SHADER\n"