diff --git a/src/OpenGL/libGLESv2/libGLESv2.cpp b/src/OpenGL/libGLESv2/libGLESv2.cpp
index ef00cc3..fd856e5 100644
--- a/src/OpenGL/libGLESv2/libGLESv2.cpp
+++ b/src/OpenGL/libGLESv2/libGLESv2.cpp
@@ -1927,10 +1927,16 @@
 			framebuffer->setStencilbuffer(GL_RENDERBUFFER, renderbuffer);
 			break;
 		default:
-			if((attachment - GL_COLOR_ATTACHMENT0) >= MAX_COLOR_ATTACHMENTS)
+			if(attachment < GL_COLOR_ATTACHMENT0 || attachment > GL_COLOR_ATTACHMENT31)
 			{
 				return error(GL_INVALID_ENUM);
 			}
+
+			if((attachment - GL_COLOR_ATTACHMENT0) >= MAX_COLOR_ATTACHMENTS)
+			{
+				return error(GL_INVALID_OPERATION);
+			}
+
 			framebuffer->setColorbuffer(GL_RENDERBUFFER, renderbuffer, attachment - GL_COLOR_ATTACHMENT0);
 			break;
 		}
@@ -2036,10 +2042,16 @@
 			framebuffer->setStencilbuffer(textarget, texture, level);
 			break;
 		default:
-			if((attachment - GL_COLOR_ATTACHMENT0) >= MAX_COLOR_ATTACHMENTS)
+			if(attachment < GL_COLOR_ATTACHMENT0 || attachment > GL_COLOR_ATTACHMENT31)
 			{
 				return error(GL_INVALID_ENUM);
 			}
+
+			if((attachment - GL_COLOR_ATTACHMENT0) >= MAX_COLOR_ATTACHMENTS)
+			{
+				return error(GL_INVALID_OPERATION);
+			}
+
 			framebuffer->setColorbuffer(textarget, texture, attachment - GL_COLOR_ATTACHMENT0, level);
 			break;
 		}
@@ -2614,14 +2626,21 @@
 			}
 			break;
 		default:
-			if((unsigned int)(attachment - GL_COLOR_ATTACHMENT0) < MAX_COLOR_ATTACHMENTS)
+			if(framebufferName == 0)
 			{
-				if(framebufferName == 0)
-				{
-					return error(GL_INVALID_OPERATION);
-				}
+				return error(GL_INVALID_OPERATION);
 			}
-			else return error(GL_INVALID_ENUM);
+
+			if(attachment < GL_COLOR_ATTACHMENT0 || attachment > GL_COLOR_ATTACHMENT31)
+			{
+				return error(GL_INVALID_ENUM);
+			}
+
+			if((attachment - GL_COLOR_ATTACHMENT0) >= MAX_COLOR_ATTACHMENTS)
+			{
+				return error(GL_INVALID_OPERATION);
+			}
+			break;
 		}
 
 		es2::Framebuffer *framebuffer = context->getFramebuffer(framebufferName);
@@ -6063,10 +6082,16 @@
 		case GL_DEPTH_ATTACHMENT:   framebuffer->setDepthbuffer(textarget, texture, level);   break;
 		case GL_STENCIL_ATTACHMENT: framebuffer->setStencilbuffer(textarget, texture, level); break;
 		default:
-			if((attachment - GL_COLOR_ATTACHMENT0) >= MAX_COLOR_ATTACHMENTS)
+			if(attachment < GL_COLOR_ATTACHMENT0 || attachment > GL_COLOR_ATTACHMENT31)
 			{
 				return error(GL_INVALID_ENUM);
 			}
+
+			if((attachment - GL_COLOR_ATTACHMENT0) >= MAX_COLOR_ATTACHMENTS)
+			{
+				return error(GL_INVALID_OPERATION);
+			}
+
 			framebuffer->setColorbuffer(textarget, texture, attachment - GL_COLOR_ATTACHMENT0, level);
 			break;
 		}
diff --git a/src/OpenGL/libGLESv2/libGLESv3.cpp b/src/OpenGL/libGLESv2/libGLESv3.cpp
index 2669739..6ba4c9d 100644
--- a/src/OpenGL/libGLESv2/libGLESv3.cpp
+++ b/src/OpenGL/libGLESv2/libGLESv3.cpp
@@ -1294,40 +1294,6 @@
 
 		switch(attachment)
 		{
-		case GL_COLOR_ATTACHMENT0:
-		case GL_COLOR_ATTACHMENT1:
-		case GL_COLOR_ATTACHMENT2:
-		case GL_COLOR_ATTACHMENT3:
-		case GL_COLOR_ATTACHMENT4:
-		case GL_COLOR_ATTACHMENT5:
-		case GL_COLOR_ATTACHMENT6:
-		case GL_COLOR_ATTACHMENT7:
-		case GL_COLOR_ATTACHMENT8:
-		case GL_COLOR_ATTACHMENT9:
-		case GL_COLOR_ATTACHMENT10:
-		case GL_COLOR_ATTACHMENT11:
-		case GL_COLOR_ATTACHMENT12:
-		case GL_COLOR_ATTACHMENT13:
-		case GL_COLOR_ATTACHMENT14:
-		case GL_COLOR_ATTACHMENT15:
-		case GL_COLOR_ATTACHMENT16:
-		case GL_COLOR_ATTACHMENT17:
-		case GL_COLOR_ATTACHMENT18:
-		case GL_COLOR_ATTACHMENT19:
-		case GL_COLOR_ATTACHMENT20:
-		case GL_COLOR_ATTACHMENT21:
-		case GL_COLOR_ATTACHMENT22:
-		case GL_COLOR_ATTACHMENT23:
-		case GL_COLOR_ATTACHMENT24:
-		case GL_COLOR_ATTACHMENT25:
-		case GL_COLOR_ATTACHMENT26:
-		case GL_COLOR_ATTACHMENT27:
-		case GL_COLOR_ATTACHMENT28:
-		case GL_COLOR_ATTACHMENT29:
-		case GL_COLOR_ATTACHMENT30:
-		case GL_COLOR_ATTACHMENT31:
-			framebuffer->setColorbuffer(textarget, texture, attachment - GL_COLOR_ATTACHMENT0, level, layer);
-			break;
 		case GL_DEPTH_ATTACHMENT:
 			framebuffer->setDepthbuffer(textarget, texture, level, layer);
 			break;
@@ -1339,7 +1305,18 @@
 			framebuffer->setStencilbuffer(textarget, texture, level, layer);
 			break;
 		default:
-			return error(GL_INVALID_ENUM);
+			if(attachment < GL_COLOR_ATTACHMENT0 || attachment > GL_COLOR_ATTACHMENT31)
+			{
+				return error(GL_INVALID_ENUM);
+			}
+
+			if((attachment - GL_COLOR_ATTACHMENT0) >= MAX_COLOR_ATTACHMENTS)
+			{
+				return error(GL_INVALID_OPERATION);
+			}
+
+			framebuffer->setColorbuffer(textarget, texture, attachment - GL_COLOR_ATTACHMENT0, level, layer);
+			break;
 		}
 	}
 }