diff --git a/android/core/src/processing/core/PGraphicsAndroid3D.java b/android/core/src/processing/core/PGraphicsAndroid3D.java
index b498b93ad..3f74d86c6 100644
--- a/android/core/src/processing/core/PGraphicsAndroid3D.java
+++ b/android/core/src/processing/core/PGraphicsAndroid3D.java
@@ -1495,12 +1495,8 @@ public class PGraphicsAndroid3D extends PGraphics {
     pgl.glViewport(savedViewport[0], savedViewport[1], savedViewport[2], savedViewport[3]);
     
     if (primarySurface) {
-      // glFlush should be called only once, since it is an expensive
-      // operation. Thus, only the main renderer (the primary surface)
-      // should call it at the end of draw, and none of the offscreen 
-      // renderers...
+      pgl.glFlush();
       pgl.endOnscreenDraw(clearColorBuffer0);
-      pgl.glFlush();                  
       pgl.releaseContext();
     } else {
       if (offscreenMultisample) {
diff --git a/java/libraries/opengl/src/processing/opengl/PGraphicsOpenGL.java b/java/libraries/opengl/src/processing/opengl/PGraphicsOpenGL.java
index 618bfbb9f..bebb703e6 100644
--- a/java/libraries/opengl/src/processing/opengl/PGraphicsOpenGL.java
+++ b/java/libraries/opengl/src/processing/opengl/PGraphicsOpenGL.java
@@ -1502,12 +1502,8 @@ public class PGraphicsOpenGL extends PGraphics {
     pgl.glViewport(savedViewport[0], savedViewport[1], savedViewport[2], savedViewport[3]);
     
     if (primarySurface) {
-      // glFlush should be called only once, since it is an expensive
-      // operation. Thus, only the main renderer (the primary surface)
-      // should call it at the end of draw, and none of the offscreen 
-      // renderers...
+      pgl.glFlush(); 
       pgl.endOnscreenDraw(clearColorBuffer0);
-      pgl.glFlush();                  
       pgl.releaseContext();
     } else {
       if (offscreenMultisample) {