diff --git a/GraphicsView/include/CGAL/Qt/Basic_viewer_qt.h b/GraphicsView/include/CGAL/Qt/Basic_viewer_qt.h
index aca57cd2ba9..6f81ab8035d 100644
--- a/GraphicsView/include/CGAL/Qt/Basic_viewer_qt.h
+++ b/GraphicsView/include/CGAL/Qt/Basic_viewer_qt.h
@@ -162,12 +162,12 @@ const char vertex_source_color_comp[] =
     "void main(void)\n"
     "{\n"
     "   fP = mv_matrix * vertex; \n"
-    "   mat3 mv_matrix_3; \n"
+    "   highp mat3 mv_matrix_3; \n"
     "   mv_matrix_3[0] = mv_matrix[0].xyz; \n"
     "   mv_matrix_3[1] = mv_matrix[1].xyz; \n"
     "   mv_matrix_3[2] = mv_matrix[2].xyz; \n"
     "   fN = mv_matrix_3* normal;  \n"
-    "   fColor = vec4(color, 1.0); \n"
+    "   fColor = highp vec4(color, 1.0); \n"
     "   gl_PointSize = point_size;\n"
     "   gl_Position = mvp_matrix * vertex;\n"
     "}"
@@ -178,24 +178,24 @@ const char fragment_source_color_comp[] =
     "varying highp vec4 fP; \n"
     "varying highp vec3 fN; \n"
     "varying highp vec4 fColor; \n"
-    "uniform vec4 light_pos;  \n"
-    "uniform vec4 light_diff; \n"
-    "uniform vec4 light_spec; \n"
-    "uniform vec4 light_amb;  \n"
-    "uniform float spec_power ; \n"
+    "uniform highp vec4 light_pos;  \n"
+    "uniform highp vec4 light_diff; \n"
+    "uniform highp vec4 light_spec; \n"
+    "uniform highp vec4 light_amb;  \n"
+    "uniform highp float spec_power ; \n"
     
     "void main(void) { \n"
     
-    "   vec3 L = light_pos.xyz - fP.xyz; \n"
-    "   vec3 V = -fP.xyz; \n"
+    "   highp vec3 L = light_pos.xyz - fP.xyz; \n"
+    "   highp vec3 V = -fP.xyz; \n"
     
-    "   vec3 N = normalize(fN); \n"
+    "   highp vec3 N = normalize(fN); \n"
     "   L = normalize(L); \n"
     "   V = normalize(V); \n"
     
-    "   vec3 R = reflect(-L, N); \n"
-    "   vec4 diffuse = max(dot(N,L), 0.0) * light_diff * fColor; \n"
-    "   vec4 specular = pow(max(dot(R,V), 0.0), spec_power) * light_spec; \n"
+    "   highp vec3 R = reflect(-L, N); \n"
+    "   highp vec4 diffuse = max(dot(N,L), 0.0) * light_diff * fColor; \n"
+    "   highp vec4 specular = pow(max(dot(R,V), 0.0), spec_power) * light_spec; \n"
     
     "gl_FragColor = light_amb*fColor + diffuse  ; \n"
     "} \n"
@@ -212,7 +212,7 @@ const char vertex_source_p_l_comp[] =
     "void main(void)\n"
     "{\n"
     "   gl_PointSize = point_size;\n"
-    "   fColor = vec4(color, 1.0); \n"
+    "   fColor = highp vec4(color, 1.0); \n"
     "   gl_Position = mvp_matrix * vertex;\n"
     "}"
   };
diff --git a/Polyhedron/demo/Polyhedron/resources/compatibility_shaders/shader_with_light.frag b/Polyhedron/demo/Polyhedron/resources/compatibility_shaders/shader_with_light.frag
index d00eb11a9a2..9a2c7d552dd 100644
--- a/Polyhedron/demo/Polyhedron/resources/compatibility_shaders/shader_with_light.frag
+++ b/Polyhedron/demo/Polyhedron/resources/compatibility_shaders/shader_with_light.frag
@@ -44,7 +44,7 @@ void main(void) {
     gl_FragColor = vec4(d,d,d,1.0);
   else
   {
-    vec4 my_color = vec4(color.xyz, 1.0);
+    highp vec4 my_color = highp vec4(color.xyz, 1.0);
     highp vec3 L = light_pos.xyz - fP.xyz;
     highp vec3 V = -fP.xyz;
     highp vec3 N;
@@ -55,16 +55,16 @@ void main(void) {
     L = normalize(L);
     V = normalize(V);
     highp vec3 R = reflect(-L, N);
-    vec4 diffuse;
+    highp vec4 diffuse;
     if(is_two_side == 1)
       diffuse = abs(dot(N,L)) * light_diff * color;
     else
       diffuse = max(dot(N,L), 0.0) * light_diff * my_color;
     highp vec4 specular = pow(max(dot(R,V), 0.0), spec_power) * light_spec;
-    vec4 ret_color = vec4((my_color*light_amb).xyz + diffuse.xyz + specular.xyz,1);
+    vec4 ret_color = highp vec4((my_color*light_amb).xyz + diffuse.xyz + specular.xyz,1);
     if(is_selected)
-      gl_FragColor = vec4(ret_color.r+70.0/255.0, ret_color.g+70.0/255.0, ret_color.b+70.0/255.0, alpha);
+      gl_FragColor = highp vec4(ret_color.r+70.0/255.0, ret_color.g+70.0/255.0, ret_color.b+70.0/255.0, alpha);
     else
-      gl_FragColor = vec4(ret_color.xyz, alpha);
+      gl_FragColor = highp vec4(ret_color.xyz, alpha);
   }
 }