diff --git a/src/org/nwapw/abacus/tree/TokenType.java b/src/org/nwapw/abacus/tree/TokenType.java
index 1d70998..b5629b5 100644
--- a/src/org/nwapw/abacus/tree/TokenType.java
+++ b/src/org/nwapw/abacus/tree/TokenType.java
@@ -7,7 +7,7 @@ package org.nwapw.abacus.tree;
 public enum TokenType {
 
     INTERNAL_FUNCTION_END(-1),
-    ANY(0), COMMA(1), OP(2), NUM(3), FUNCTION(4), OPEN_PARENTH(5), CLOSE_PARENTH(6);
+    ANY(0), WHITESPACE(1), COMMA(2), OP(3), NUM(4), FUNCTION(5), OPEN_PARENTH(6), CLOSE_PARENTH(7);
 
     /**
      * The priority by which this token gets sorted.
diff --git a/src/org/nwapw/abacus/tree/TreeBuilder.java b/src/org/nwapw/abacus/tree/TreeBuilder.java
index 30e9a5d..ea269af 100644
--- a/src/org/nwapw/abacus/tree/TreeBuilder.java
+++ b/src/org/nwapw/abacus/tree/TreeBuilder.java
@@ -35,6 +35,7 @@ public class TreeBuilder {
      */
     public TreeBuilder(){
         lexer = new Lexer<TokenType>(){{
+            register(" ", TokenType.WHITESPACE);
             register(",", TokenType.COMMA);
             register("[0-9]+(\\.[0-9]+)?", TokenType.NUM);
             register("\\(", TokenType.OPEN_PARENTH);
@@ -98,12 +99,14 @@ public class TreeBuilder {
                 while(!tokenStack.empty()) {
                     Match<TokenType> otherMatch = tokenStack.peek();
                     TokenType otherMatchType = otherMatch.getType();
-                    if(otherMatchType != TokenType.OP) break;
+                    if(!(otherMatchType == TokenType.OP || otherMatchType == TokenType.FUNCTION)) break;
 
-                    int otherPrecdence = precedenceMap.get(source.substring(otherMatch.getFrom(), otherMatch.getTo()));
-                    if(otherPrecdence < precedence ||
-                            (associativity == OperatorAssociativity.RIGHT && otherPrecdence == precedence)) {
-                        break;
+                    if(otherMatchType == TokenType.OP){
+                        int otherPrecdence = precedenceMap.get(source.substring(otherMatch.getFrom(), otherMatch.getTo()));
+                        if(otherPrecdence < precedence ||
+                                (associativity == OperatorAssociativity.RIGHT && otherPrecdence == precedence)) {
+                            break;
+                        }
                     }
                     output.add(tokenStack.pop());
                 }
@@ -169,6 +172,7 @@ public class TreeBuilder {
     public TreeNode fromString(String string){
         ArrayList<Match<TokenType>> matches = tokenize(string);
         if(matches == null) return null;
+        matches.removeIf(m -> m.getType() == TokenType.WHITESPACE);
         matches = intoPostfix(string, matches);
         if(matches == null) return null;