diff --git a/source/blender/gpu/metal/kernels/compute_texture_read.msl b/source/blender/gpu/metal/kernels/compute_texture_read.msl
index 41d7b312dbd..6c099024f7a 100644
--- a/source/blender/gpu/metal/kernels/compute_texture_read.msl
+++ b/source/blender/gpu/metal/kernels/compute_texture_read.msl
@@ -62,11 +62,24 @@ template<> uint denormalize<uint>(float val)
   return uint(float(DEPTH_SCALE_FACTOR) * val);
 }
 
+/* Float to other type case. */
 template<typename T> T convert_type(float type)
 {
   return T(type);
 }
 
+/* Uint to other types. */
+template<typename T> T convert_type(uint type)
+{
+  return T(type);
+}
+
+/* Int to other types. */
+template<typename T> T convert_type(int type)
+{
+  return T(type);
+}
+
 template<> uchar convert_type<uchar>(float val)
 {
   return uchar(val * float(0xFF));
@@ -141,8 +154,8 @@ kernel void compute_texture_read(constant TextureReadParams &params [[buffer(0)]
   uint xx = position[0];
   uint yy = position[1];
   uint zz = position[2];
-  int index = (zz * (params.extent[0] * params.extent[1]) + yy * params.extnt[0] + xx) *
-              COMPONENT_COUNT_INPUT;
+  int index = (zz * (params.extent[0] * params.extent[1]) + yy * params.extent[0] + xx) *
+              COMPONENT_COUNT_OUTPUT;
   read_colour = read_tex.read(uint3(params.offset[0], params.offset[1], params.offset[2]) +
                               uint3(xx, yy, zz));
 
@@ -163,7 +176,7 @@ kernel void compute_texture_read(constant TextureReadParams &params [[buffer(0)]
   uint yy = position[1];
   uint layer = position[2];
   int index = (layer * (params.extent[0] * params.extent[1]) + yy * params.extent[0] + xx) *
-              COMPONENT_COUNT_INPUT;
+              COMPONENT_COUNT_OUTPUT;
 
   /* Read data */
 #  if IS_DEPTH_FORMAT == 1
diff --git a/source/blender/gpu/metal/mtl_framebuffer.mm b/source/blender/gpu/metal/mtl_framebuffer.mm
index 5e3a4136d88..86b7601a3cc 100644
--- a/source/blender/gpu/metal/mtl_framebuffer.mm
+++ b/source/blender/gpu/metal/mtl_framebuffer.mm
@@ -606,17 +606,6 @@ void MTLFrameBuffer::update_attachments(bool update_viewport)
   if (!dirty_attachments_) {
     return;
   }
-
-  /* Cache viewport and scissor (If we have existing attachments). */
-  int t_viewport[4], t_scissor[4];
-  update_viewport = update_viewport &&
-                    (this->get_attachment_count() > 0 && this->has_depth_attachment() &&
-                     this->has_stencil_attachment());
-  if (update_viewport) {
-    this->viewport_get(t_viewport);
-    this->scissor_get(t_scissor);
-  }
-
   /* Clear current attachments state. */
   this->remove_all_attachments();
 
@@ -738,22 +727,25 @@ void MTLFrameBuffer::update_attachments(bool update_viewport)
     }
   }
 
-  /* Check whether the first attachment is SRGB. */
+  /* Extract attachment size and determine if framebuffer is SRGB. */
   if (first_attachment != GPU_FB_MAX_ATTACHMENT) {
-    srgb_ = (first_attachment_mtl.texture->format_get() == GPU_SRGB8_A8);
-  }
-
-  /* Reset viewport and Scissor (If viewport is smaller or equal to the framebuffer size). */
-  if (update_viewport && t_viewport[2] <= width_ && t_viewport[3] <= height_) {
-
-    this->viewport_set(t_viewport);
-    this->scissor_set(t_viewport);
+    /* Ensure size is correctly assigned. */
+    GPUAttachment &attach = attachments_[first_attachment];
+    int size[3];
+    GPU_texture_get_mipmap_size(attach.tex, attach.mip, size);
+    this->size_set(size[0], size[1]);
+    srgb_ = (GPU_texture_format(attach.tex) == GPU_SRGB8_A8);
   }
   else {
-    this->viewport_reset();
-    this->scissor_reset();
+    /* Empty frame-buffer. */
+    width_ = 0;
+    height_ = 0;
   }
 
+  /* Reset viewport and Scissor. */
+  this->viewport_reset();
+  this->scissor_reset();
+
   /* We have now updated our internal structures. */
   dirty_attachments_ = false;
 }