diff --git a/parser.cpp b/parser.cpp
index d516378..0906fa8 100644
--- a/parser.cpp
+++ b/parser.cpp
@@ -265,8 +265,8 @@ std::vector<TreeNode> TreeNode::parseExpression(std::vector<TreeNode> input) {
       parsedExpression[openCurlyBrace].text = "{}";
     }
   for (int i = parsedExpression.size() - 1; i >= 0;
-       i--) // The unary "-" operator.
-    if (parsedExpression[i].text == "-" and
+       i--) // The unary "+" and "-" operators.
+    if ((parsedExpression[i].text == "-" or parsedExpression[i].text == "+") and
         i != int(parsedExpression.size()) - 1 and
         parsedExpression[i].children.size() == 0 and
         (!i or (!isComposedOfAlnumsAndOneDot(parsedExpression[i - 1].text) and
diff --git a/tests.cpp b/tests.cpp
index 10a4609..aaaf2fe 100644
--- a/tests.cpp
+++ b/tests.cpp
@@ -132,7 +132,8 @@ void interpreterTests() {
 	       not(2 < 3 < 1) and
 	       (-3 < -2 < -1) and
 	       (3 > 2 > 1)
-       )", "1"}
+       )", "1"},
+       {"5 + + 1", "6"}
       });
   for (unsigned int i = 0; i < tests.size(); i++) {
     std::string result = std::to_string(