diff --git a/src/App/ExpressionParser.l b/src/App/ExpressionParser.l
index 3965dd7c98..66c4435957 100644
--- a/src/App/ExpressionParser.l
+++ b/src/App/ExpressionParser.l
@@ -61,6 +61,7 @@ extern int column;
 %option noyywrap nounput
 
 /* UTF-8 unicode regular expressions. */
+/* http://www.unicode.org/reports/tr44/#General_Category_Values */
 
 Cc	([\x00-\x1f\x7f]|\xc2[\x80-\x9f])
 Cf	(\xc2\xad|\xd8[\x80-\x85\x9c]|\xdb\x9d|\xdc\x8f|\xe1(\xa0\x8e)|\xe2(\x80[\x8b-\x8f\xaa-\xae]|\x81[\xa0-\xa4\xa6-\xaf])|\xef(\xbb\xbf|\xbf[\xb9-\xbb])|\xf0(\x91(\x82\xbd))|\xf3(\xa0(\x80\x81)))
diff --git a/src/App/ExpressionParser.sh b/src/App/ExpressionParser.sh
index ba14525792..bb12396b7a 100755
--- a/src/App/ExpressionParser.sh
+++ b/src/App/ExpressionParser.sh
@@ -1,3 +1,6 @@
-# Description for bash script
-flex -olex.ExpressionParser.c < ExpressionParser.l
-bison -oExpressionParser.tab.c ExpressionParser.y
+#!/usr/bin/env sh
+
+cd "$(dirname "$0")"
+
+flex -v -olex.ExpressionParser.c ExpressionParser.l
+bison -d -v -Wall -oExpressionParser.tab.c ExpressionParser.y
diff --git a/src/App/ExpressionParser.y b/src/App/ExpressionParser.y
index e49d9a34e5..0a3a1f25e9 100644
--- a/src/App/ExpressionParser.y
+++ b/src/App/ExpressionParser.y
@@ -36,7 +36,6 @@ std::stack<FunctionExpression::Function> functions;                /**< Function
        #define yyerror ExpressionParser_yyerror
 %}
 
-     /* Bison declarations.  */
      %token FUNC
      %token ONE
      %token NUM
@@ -66,16 +65,14 @@ std::stack<FunctionExpression::Function> functions;                /**< Function
      %type <string_or_identifier> document
      %type <string_or_identifier> object
      %type <ivalue> integer
-     %left ONE NUM INTEGER CONSTANT
-     %left EQ NEQ LT GT GTE LTE
-     %left '?' ':'
+     %precedence EQ NEQ LT GT GTE LTE
+     %precedence ':'
      %left MINUSSIGN '+'
      %left '*' '/' '%'
      %precedence NUM_AND_UNIT
-     %left '^'    /* exponentiation */
-     %left EXPONENT
-     %left NEG     /* negation--unary minus */
-     %left POS     /* unary plus */
+     %left '^'
+     %precedence NEG
+     %precedence POS
 
 %destructor { delete $$; } num range exp cond unit_exp indexable
 %destructor { delete $$; } <component>
@@ -105,6 +102,7 @@ exp:      num                			{ $$ = $1;
         | indexable       			    { $$ = $1;                                                                        }
         | FUNC  args ')'  		        { $$ = new FunctionExpression(DocumentObject, $1.first, std::move($1.second), $2);        }
         | cond '?' exp ':' exp                  { $$ = new ConditionalExpression(DocumentObject, $1, $3, $5);                     }
+        | '(' exp ')'                           { $$ = $2; }
         ;
 
 num:       ONE                                  { $$ = new NumberExpression(DocumentObject, Quantity($1));                        }
@@ -129,6 +127,7 @@ cond: exp EQ exp                                { $$ = new OperatorExpression(Do
     | exp GT exp                                { $$ = new OperatorExpression(DocumentObject, $1, OperatorExpression::GT, $3);    }
     | exp GTE exp                               { $$ = new OperatorExpression(DocumentObject, $1, OperatorExpression::GTE, $3);   }
     | exp LTE exp                               { $$ = new OperatorExpression(DocumentObject, $1, OperatorExpression::LTE, $3);   }
+    | '(' cond ')'                              { $$ = $2; }
     ;
 
 unit_exp: UNIT                                  { $$ = new UnitExpression(DocumentObject, $1.scaler, $1.unitStr );                }
@@ -206,8 +205,7 @@ indexer
     ;
 
 indexable
-    : '(' exp ')'                           { $$ = $2; }
-    | identifier indexer                    { $$ = new VariableExpression(DocumentObject,$1); $$->addComponent($2); }
+    : identifier indexer                    { $$ = new VariableExpression(DocumentObject,$1); $$->addComponent($2); }
     | indexable indexer                     { $1->addComponent(std::move($2)); $$ = $1; }
     | indexable '.' IDENTIFIER              { $1->addComponent(Expression::createComponent($3)); $$ = $1; }
     ;
diff --git a/src/Mod/Spreadsheet/TestSpreadsheet.py b/src/Mod/Spreadsheet/TestSpreadsheet.py
index c81d4cc6f3..727309d3e1 100644
--- a/src/Mod/Spreadsheet/TestSpreadsheet.py
+++ b/src/Mod/Spreadsheet/TestSpreadsheet.py
@@ -46,7 +46,6 @@ class SpreadsheetCases(unittest.TestCase):
     def testAggregates(self):
         """ Test all aggregate functions """
         sheet = self.doc.addObject('Spreadsheet::Sheet','Spreadsheet')
-        sheet = self.doc.addObject('Spreadsheet::Sheet','Spreadsheet')
         sheet.set('B13',  '4')
         sheet.set('B14',  '5')
         sheet.set('B15',  '6')
@@ -165,7 +164,6 @@ class SpreadsheetCases(unittest.TestCase):
 
     def testFunctions(self):
         """ Test all built-in simple functions """
-        doc = FreeCAD.newDocument()
         sheet = self.doc.addObject('Spreadsheet::Sheet','Spreadsheet')
         sheet.set('A1',  '=cos(60)')   # Cos
         sheet.set('B1',  '=cos(60deg)')
@@ -366,7 +364,6 @@ class SpreadsheetCases(unittest.TestCase):
         self.assertMostlyEqual(sheet.B27, l)
         self.assertTrue(sheet.C27.startswith(u'ERR: Units must be equal'))
         self.assertMostlyEqual(sheet.D27, Units.Quantity("3 mm"))
-        FreeCAD.closeDocument(doc.Name)
 
     def testRelationalOperators(self):
         """ Test relational operators """
@@ -1442,6 +1439,15 @@ class SpreadsheetCases(unittest.TestCase):
         sheet.setAlias('A1', 'aliasOfEmptyCell')
         self.assertEqual(sheet.getCellFromAlias("aliasOfEmptyCell"),"A1")
 
+    def testParensAroundCondition(self):
+        """ Parens around a condition should be accepted """
+        sheet = self.doc.addObject('Spreadsheet::Sheet','Spreadsheet')
+
+        sheet.set('A1', '=(1 == 1) ? 1 : 0')
+        self.doc.recompute()
+        self.assertEqual(sheet.getContents('A1'), '=1 == 1 ? 1 : 0')
+        self.assertEqual(sheet.A1, 1)
+
     def tearDown(self):
         #closing doc
         FreeCAD.closeDocument(self.doc.Name)