diff --git a/gsk/gl/resources/border.glsl b/gsk/gl/resources/border.glsl
index 0fa3203887adfe8c106eb46c4d35ba87bd89f937..cf5955f307cb7b803397a4fbaf1f1ed31556b4aa 100644
--- a/gsk/gl/resources/border.glsl
+++ b/gsk/gl/resources/border.glsl
@@ -2,11 +2,16 @@
 // border.glsl
 
 uniform vec4 u_widths;
-uniform vec4[3] u_outline_rect;
+uniform vec4 u_outline_rect[3];
 
 _OUT_ vec4 final_color;
+#if defined(GSK_GLES) || defined(GSK_LEGACY)
+_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline[3];
+_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline[3];
+#else
 _OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline;
 _OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline;
+#endif
 
 void main() {
   gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);
@@ -29,11 +34,16 @@ void main() {
 // FRAGMENT_SHADER:
 // border.glsl
 
-uniform vec4[3] u_outline_rect;
+uniform vec4 u_outline_rect[3];
 
 _IN_ vec4 final_color;
+#if defined(GSK_GLES) || defined(GSK_LEGACY)
+_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline[3];
+_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline[3];
+#else
 _IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline;
 _IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline;
+#endif
 
 void main() {
   vec2 frag = gsk_get_frag_coord();
diff --git a/gsk/gl/resources/filled_border.glsl b/gsk/gl/resources/filled_border.glsl
index 23af3aa89c605f814019397f09da2a83745eea57..e5320cff0808e708090bbe7522e0b705606a2bee 100644
--- a/gsk/gl/resources/filled_border.glsl
+++ b/gsk/gl/resources/filled_border.glsl
@@ -2,12 +2,17 @@
 // filled_border.glsl
 
 uniform vec4 u_widths;
-uniform vec4[3] u_outline_rect;
+uniform vec4 u_outline_rect[3];
 
 _OUT_ vec4 outer_color;
 _OUT_ vec4 inner_color;
+#if defined(GSK_GLES) || defined(GSK_LEGACY)
+_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline[3];
+_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline[3];
+#else
 _OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline;
 _OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline;
+#endif
 
 void main() {
   gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);
@@ -31,12 +36,17 @@ void main() {
 // FRAGMENT_SHADER:
 // filled_border.glsl
 
-uniform vec4[3] u_outline_rect;
+uniform vec4 u_outline_rect[3];
 
 _IN_ vec4 outer_color;
 _IN_ vec4 inner_color;
+#if defined(GSK_GLES) || defined(GSK_LEGACY)
+_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline[3];
+_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline[3];
+#else
 _IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline;
 _IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline;
+#endif
 
 void main() {
   vec2 frag = gsk_get_frag_coord();
diff --git a/gsk/gl/resources/inset_shadow.glsl b/gsk/gl/resources/inset_shadow.glsl
index 83d4287f130c7dab1af094299e7d30723a1eb139..651587e27a75e5909a748ed028363bc24f2014e5 100644
--- a/gsk/gl/resources/inset_shadow.glsl
+++ b/gsk/gl/resources/inset_shadow.glsl
@@ -3,11 +3,16 @@
 
 uniform float u_spread;
 uniform vec2 u_offset;
-uniform vec4[3] u_outline_rect;
+uniform vec4 u_outline_rect[3];
 
 _OUT_ vec4 final_color;
+#if defined(GSK_GLES) || defined(GSK_LEGACY)
+_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline[3];
+_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline[3];
+#else
 _OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline;
 _OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline;
+#endif
 
 void main() {
   gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);
@@ -33,8 +38,13 @@ void main() {
 // inset_shadow.glsl
 
 _IN_ vec4 final_color;
+#if defined(GSK_GLES) || defined(GSK_LEGACY)
+_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline[3];
+_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline[3];
+#else
 _IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline;
 _IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline;
+#endif
 
 void main() {
   vec2 frag = gsk_get_frag_coord();
diff --git a/gsk/gl/resources/outset_shadow.glsl b/gsk/gl/resources/outset_shadow.glsl
index fac86c0093c9ec49e0aa4bddbfca834ba640a205..71b49e28b71e112856175a1f3d68380ca2c36ce5 100644
--- a/gsk/gl/resources/outset_shadow.glsl
+++ b/gsk/gl/resources/outset_shadow.glsl
@@ -1,10 +1,14 @@
 // VERTEX_SHADER:
 // outset_shadow.glsl
 
-uniform vec4[3] u_outline_rect;
+uniform vec4 u_outline_rect[3];
 
 _OUT_ vec4 final_color;
+#if defined(GSK_GLES) || defined(GSK_LEGACY)
+_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outline[3];
+#else
 _OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outline;
+#endif
 
 void main() {
   gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);
@@ -23,7 +27,11 @@ void main() {
 // outset_shadow.glsl
 
 _IN_ vec4 final_color;
+#if defined(GSK_GLES) || defined(GSK_LEGACY)
+_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outline[3];
+#else
 _IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outline;
+#endif
 
 void main() {
   vec2 frag = gsk_get_frag_coord();
diff --git a/gsk/gl/resources/preamble.fs.glsl b/gsk/gl/resources/preamble.fs.glsl
index 0c366bd8476ea01c909f0d52b0eb1f659b7d72cc..56389c16d654e49d04f93dfd57df57bb3c4e54db 100644
--- a/gsk/gl/resources/preamble.fs.glsl
+++ b/gsk/gl/resources/preamble.fs.glsl
@@ -3,7 +3,7 @@ uniform mat4 u_projection;
 uniform mat4 u_modelview;
 uniform float u_alpha;
 uniform vec4 u_viewport;
-uniform vec4[3] u_clip_rect;
+uniform vec4 u_clip_rect[3];
 
 #if defined(GSK_LEGACY)
 _OUT_ vec4 outputColor;
@@ -14,7 +14,11 @@ _OUT_ vec4 outputColor;
 _IN_ vec2 vUv;
 
 
+#if defined(GSK_GLES) || defined(GSK_LEGACY)
+GskRoundedRect gsk_decode_rect(_GSK_ROUNDED_RECT_UNIFORM_ r[3])
+#else
 GskRoundedRect gsk_decode_rect(_GSK_ROUNDED_RECT_UNIFORM_ r)
+#endif
 {
   GskRoundedRect rect;
 #if defined(GSK_GLES) || defined(GSK_LEGACY)
diff --git a/gsk/gl/resources/preamble.glsl b/gsk/gl/resources/preamble.glsl
index 46bebc14e0477fde28db8914e6056c2decb384b3..e93ebeb52b36aba6f7c581fd21bb470dca9c6e32 100644
--- a/gsk/gl/resources/preamble.glsl
+++ b/gsk/gl/resources/preamble.glsl
@@ -5,7 +5,7 @@ precision highp float;
 #if defined(GSK_GLES) || defined(GSK_LEGACY)
 #define _OUT_ varying
 #define _IN_ varying
-#define _GSK_ROUNDED_RECT_UNIFORM_ vec4[3]
+#define _GSK_ROUNDED_RECT_UNIFORM_ vec4
 #else
 #define _OUT_ out
 #define _IN_ in
@@ -73,7 +73,7 @@ void gsk_bounds_normalize (inout vec4 bounds)
 
 // Transform from a C GskRoundedRect to what we need.
 GskRoundedRect
-gsk_create_rect(vec4[3] data)
+gsk_create_rect(vec4 data[3])
 {
   vec4 bounds = vec4(data[0].xy, data[0].xy + data[0].zw);
 
@@ -90,7 +90,7 @@ gsk_create_rect(vec4[3] data)
 }
 
 vec4
-gsk_get_bounds(vec4[3] data)
+gsk_get_bounds(vec4 data[3])
 {
   vec4 bounds = vec4(data[0].xy, data[0].xy + data[0].zw);
 
diff --git a/gsk/gl/resources/preamble.vs.glsl b/gsk/gl/resources/preamble.vs.glsl
index 758bca89d200e57457dc691f64b10d0776c461ef..1b3617e7b5609d610dc07c74091fe0ca6c0cbb07 100644
--- a/gsk/gl/resources/preamble.vs.glsl
+++ b/gsk/gl/resources/preamble.vs.glsl
@@ -58,6 +58,8 @@ void gsk_rounded_rect_transform(inout GskRoundedRect r, mat4 mat)
 #if defined(GSK_LEGACY)
 // Can't have out or inout array parameters...
 #define gsk_rounded_rect_encode(r, uni) uni[0] = r.bounds; uni[1] = r.corner_points1; uni[2] = r.corner_points2;
+#elif defined(GSK_GLES)
+void gsk_rounded_rect_encode(GskRoundedRect r, out _GSK_ROUNDED_RECT_UNIFORM_ out_r[3])
 #else
 void gsk_rounded_rect_encode(GskRoundedRect r, out _GSK_ROUNDED_RECT_UNIFORM_ out_r)
 {
diff --git a/gsk/gl/resources/unblurred_outset_shadow.glsl b/gsk/gl/resources/unblurred_outset_shadow.glsl
index cd44212c933f2c29721b306d903cca2d93514a8e..694e864f11c60282fb55d9c98897958d3b637183 100644
--- a/gsk/gl/resources/unblurred_outset_shadow.glsl
+++ b/gsk/gl/resources/unblurred_outset_shadow.glsl
@@ -3,11 +3,16 @@
 
 uniform float u_spread;
 uniform vec2 u_offset;
-uniform vec4[3] u_outline_rect;
+uniform vec4 u_outline_rect[3];
 
 _OUT_ vec4 final_color;
+#if defined(GSK_GLES) || defined(GSK_LEGACY)
+_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline[3];
+_OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline[3];
+#else
 _OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline;
 _OUT_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline;
+#endif
 
 void main() {
   gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);
@@ -29,8 +34,13 @@ void main() {
 // FRAGMENT_SHADER:
 // unblurred_outset_shadow.glsl
 _IN_ vec4 final_color;
+#if defined(GSK_GLES) || defined(GSK_LEGACY)
+_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline[3];
+_IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline[3];
+#else
 _IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_outside_outline;
 _IN_ _GSK_ROUNDED_RECT_UNIFORM_ transformed_inside_outline;
+#endif
 
 void main() {
   vec2 frag = gsk_get_frag_coord();