diff --git a/kalk/src/analysis.rs b/kalk/src/analysis.rs
index 7b73bac..58883ed 100644
--- a/kalk/src/analysis.rs
+++ b/kalk/src/analysis.rs
@@ -122,11 +122,7 @@ fn build_fn_decl(
             // Check if all the expressions in the parameter_expr are
             // variables. If not, it can't be turned into a function declaration.
             let all_are_vars = match &parameter_expr {
-                Expr::Vector(exprs) => {
-                    exprs
-                        .iter()
-                        .any(|x| matches!(x, Expr::Var(_)))
-                }
+                Expr::Vector(exprs) => exprs.iter().any(|x| matches!(x, Expr::Var(_))),
                 Expr::Group(expr) => {
                     matches!(&**expr, Expr::Var(_))
                 }
@@ -610,7 +606,7 @@ fn build_fn_call(
             context.sum_variable_names = Some(Vec::new());
         }
     }
-    
+
     // Don't perform equation solving on special functions
     if is_integral || is_sum_prod {
         context.in_equation = false;
@@ -775,7 +771,13 @@ fn build_var(context: &mut Context, name: &str) -> Expr {
         }
     }
 
-    if context.in_sum_prod && context.sum_variable_names.as_ref().unwrap().contains(&name.to_string()) {
+    if context.in_sum_prod
+        && context
+            .sum_variable_names
+            .as_ref()
+            .unwrap()
+            .contains(&name.to_string())
+    {
         return Expr::Var(Identifier::from_full_name(name));
     }
 
diff --git a/kalk/src/parser.rs b/kalk/src/parser.rs
index f1aa1db..063ecdb 100644
--- a/kalk/src/parser.rs
+++ b/kalk/src/parser.rs
@@ -433,7 +433,7 @@ fn parse_sum(context: &mut Context) -> Result<Expr, CalcError> {
     while match_token(context, TokenKind::Plus) || match_token(context, TokenKind::Minus) {
         let op = peek(context).kind;
         advance(context);
-        let right = parse_factor(context)?;
+        let right = parse_sum(context)?;
 
         left = Expr::Binary(Box::new(left), op, Box::new(right));
     }
@@ -447,11 +447,7 @@ fn parse_factor(context: &mut Context) -> Result<Expr, CalcError> {
     if let Expr::Unary(TokenKind::Percent, percent_left) = left.clone() {
         let try_parse = parse_factor(context);
         if try_parse.is_ok() {
-            left = Expr::Binary(
-                percent_left,
-                TokenKind::Percent,
-                Box::new(try_parse?),
-            );
+            left = Expr::Binary(percent_left, TokenKind::Percent, Box::new(try_parse?));
         }
     }
 
@@ -477,7 +473,7 @@ fn parse_factor(context: &mut Context) -> Result<Expr, CalcError> {
             _ => advance(context).kind,
         };
 
-        let right = parse_unit(context)?;
+        let right = parse_factor(context)?;
         left = Expr::Binary(Box::new(left), op, Box::new(right));
     }
 
diff --git a/tests/basics.kalker b/tests/basics.kalker
index b152313..8921502 100644
--- a/tests/basics.kalker
+++ b/tests/basics.kalker
@@ -2,4 +2,4 @@ x = 2
 y = 3
 f(x) = 2x(x - 3)(y + 2)
 
-f(f(x) + y) = 3400
\ No newline at end of file
+2f(f(x) + y) = 6800
\ No newline at end of file