diff --git a/android/core/src/processing/opengl/FillShaderVertFull.glsl b/android/core/src/processing/opengl/FillShaderVertFull.glsl
index c9a79eb50..cd6f6ce7f 100644
--- a/android/core/src/processing/opengl/FillShaderVertFull.glsl
+++ b/android/core/src/processing/opengl/FillShaderVertFull.glsl
@@ -83,10 +83,10 @@ void main() {
   // Normal vector in eye coordinates
   vec3 ecNormal = normalize(normalMatrix * inNormal);
   
-  if (dot(-ecVertex, ecNormal) < 0) {
+  if (dot(-ecVertex, ecNormal) < zero_float) {
     // If normal is away from camera, choose its opposite.
     // If we add backface culling, this will be backfacing  
-    ecNormal *= -1;
+    ecNormal *= -one_float;
   }  
   
   // Light calculations
diff --git a/android/core/src/processing/opengl/FillShaderVertLit.glsl b/android/core/src/processing/opengl/FillShaderVertLit.glsl
index 33d2360e7..7c184a807 100644
--- a/android/core/src/processing/opengl/FillShaderVertLit.glsl
+++ b/android/core/src/processing/opengl/FillShaderVertLit.glsl
@@ -80,10 +80,10 @@ void main() {
   // Normal vector in eye coordinates
   vec3 ecNormal = normalize(normalMatrix * inNormal);
   
-  if (dot(-ecVertex, ecNormal) < 0) {
+  if (dot(-ecVertex, ecNormal) < zero_float) {
     // If normal is away from camera, choose its opposite.
     // If we add backface culling, this will be backfacing  
-    ecNormal *= -1;
+    ecNormal *= -one_float;
   }
   
   // Light calculations
diff --git a/java/libraries/opengl/src/processing/opengl/FillShaderVertFull.glsl b/java/libraries/opengl/src/processing/opengl/FillShaderVertFull.glsl
index c9a79eb50..edbcb78fb 100644
--- a/java/libraries/opengl/src/processing/opengl/FillShaderVertFull.glsl
+++ b/java/libraries/opengl/src/processing/opengl/FillShaderVertFull.glsl
@@ -83,11 +83,11 @@ void main() {
   // Normal vector in eye coordinates
   vec3 ecNormal = normalize(normalMatrix * inNormal);
   
-  if (dot(-ecVertex, ecNormal) < 0) {
+  if (dot(-ecVertex, ecNormal) < zero_float) {
     // If normal is away from camera, choose its opposite.
     // If we add backface culling, this will be backfacing  
-    ecNormal *= -1;
-  }  
+    ecNormal *= -one_float;
+  }
   
   // Light calculations
   vec3 totalAmbient = vec3(0, 0, 0);
diff --git a/java/libraries/opengl/src/processing/opengl/FillShaderVertLit.glsl b/java/libraries/opengl/src/processing/opengl/FillShaderVertLit.glsl
index 33d2360e7..7c184a807 100644
--- a/java/libraries/opengl/src/processing/opengl/FillShaderVertLit.glsl
+++ b/java/libraries/opengl/src/processing/opengl/FillShaderVertLit.glsl
@@ -80,10 +80,10 @@ void main() {
   // Normal vector in eye coordinates
   vec3 ecNormal = normalize(normalMatrix * inNormal);
   
-  if (dot(-ecVertex, ecNormal) < 0) {
+  if (dot(-ecVertex, ecNormal) < zero_float) {
     // If normal is away from camera, choose its opposite.
     // If we add backface culling, this will be backfacing  
-    ecNormal *= -1;
+    ecNormal *= -one_float;
   }
   
   // Light calculations