diff --git a/shaders/dilate.f.glsl b/shaders/dilate.f.glsl
index d3cf0b1..4497bdc 100644
--- a/shaders/dilate.f.glsl
+++ b/shaders/dilate.f.glsl
@@ -27,9 +27,9 @@ void main() {
 	int size = int(floor(threshold));
 	int cutoff = size + 1;
 	float edge_weight = fract(threshold);
-	vec2 tex_size = textureSize(tex, 0).xy;
+	vec2 tex_size = vec2(textureSize(tex, 0).xy);
 
-	float a_out = 0;
+	float a_out = 0.0;
 
 	for (int x = -cutoff; x <= cutoff; x++) {
 		for (int y = -cutoff; y <= cutoff; y++) {
@@ -37,7 +37,7 @@ void main() {
 			if (d > threshold)
 				continue;
 			float a = texture(tex, tex_coord + vec2(x, y) / tex_size).r;
-			if (d > size)
+			if (d > float(size))
 				a *= edge_weight;
 			a_out += a;
 		}
diff --git a/shaders/fill_angle.f.glsl b/shaders/fill_angle.f.glsl
index e76e8b2..b2f3906 100644
--- a/shaders/fill_angle.f.glsl
+++ b/shaders/fill_angle.f.glsl
@@ -27,7 +27,7 @@ out vec4 frag_color;
 void main() {
 	vec2 p = tex_coord - center;
 	float a = atan(p.y, p.x);
-	a = mod(a - start_angle, 2 * PI);
+	a = mod(a - start_angle, 2.0 * PI);
 	if (a > angle)
 		discard;
 	frag_color = color;
diff --git a/src/video.c b/src/video.c
index 1d2def7..697fedf 100644
--- a/src/video.c
+++ b/src/video.c
@@ -36,7 +36,8 @@ struct sdl_private sdl;
 static const GLchar glsl_preamble[] =
 #ifdef USE_GLES
 	"#version 300 es\n"
-	"precision highp float;\n";
+	"precision highp float;\n"
+	"precision highp int;\n";
 #else
 	"#version 140\n";
 #endif