diff --git a/src/main.rs b/src/main.rs
index c031f48..be88fc2 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -99,7 +99,7 @@ fn main() {
 
 	match output_pretty {
 		Some("dot" | "graphdotviz") => expr.then(|e| {
-			let graph = e.create_graphviz_graph(unsafe { GLOBAL_COUNTER.next() });
+			let graph = e.create_graphviz_graph(unsafe { GRAPHVIZ_NODE_COUNTER.next() });
 			let graphviz_format = "node [shape = box, style = filled, color = \"#bfd1e5\", fontname = monospace, fontsize = 12]";
 			eprintln!("digraph {{\n{}\n{}\n}}", graphviz_format, graph);
 		}),
@@ -170,7 +170,8 @@ impl Counter {
 	}
 }
 
-static mut GLOBAL_COUNTER: Counter = Counter::new();
+// Used for numbering nodes in GraphViz printer.
+static mut GRAPHVIZ_NODE_COUNTER: Counter = Counter::new();
 
 impl Expression {
 	pub fn create_graphviz_graph(&self, id: usize) -> String {
@@ -180,7 +181,7 @@ impl Expression {
 			},
 			Expression::Literal(_) => unreachable!(),
 			Expression::Unary(op, expr) => {
-				let expr_id = unsafe { GLOBAL_COUNTER.next() };
+				let expr_id = unsafe { GRAPHVIZ_NODE_COUNTER.next() };
 
 				format!("Node{} -> Node{}\nNode{} [label = \"{}\"]\n{}",
 					id, expr_id,
@@ -188,8 +189,8 @@ impl Expression {
 					expr.create_graphviz_graph(expr_id))
 			},
 			Expression::Binary(op, left, right) => {
-				let left_id = unsafe { GLOBAL_COUNTER.next() };
-				let right_id = unsafe { GLOBAL_COUNTER.next() };
+				let left_id = unsafe { GRAPHVIZ_NODE_COUNTER.next() };
+				let right_id = unsafe { GRAPHVIZ_NODE_COUNTER.next() };
 
 				format!("Node{} -> {{ Node{} Node{} }}\nNode{} [label = \"{}\"]\n{}\n{}",
 					id, left_id, right_id,