diff --git a/gfx/drivers_shader/shader_gl_core.cpp b/gfx/drivers_shader/shader_gl_core.cpp
index 5ded102df2..496d1631c2 100644
--- a/gfx/drivers_shader/shader_gl_core.cpp
+++ b/gfx/drivers_shader/shader_gl_core.cpp
@@ -1028,7 +1028,7 @@ Size2D Pass::get_output_size(const Size2D &original,
          break;
 
       case GLSLANG_FILTER_CHAIN_SCALE_VIEWPORT:
-         width = current_viewport.width * pass_info.scale_x;
+         width = (retroarch_get_rotation() % 2 ? current_viewport.height : current_viewport.width) * pass_info.scale_x;
          break;
 
       case GLSLANG_FILTER_CHAIN_SCALE_ABSOLUTE:
@@ -1050,7 +1050,7 @@ Size2D Pass::get_output_size(const Size2D &original,
          break;
 
       case GLSLANG_FILTER_CHAIN_SCALE_VIEWPORT:
-         height = current_viewport.height * pass_info.scale_y;
+         height = (retroarch_get_rotation() % 2 ? current_viewport.width : current_viewport.height) * pass_info.scale_y;
          break;
 
       case GLSLANG_FILTER_CHAIN_SCALE_ABSOLUTE: