diff --git a/MathKit/MPExpressionView.m b/MathKit/MPExpressionView.m
old mode 100644
new mode 100755
index 8a6405d..eac3884
--- a/MathKit/MPExpressionView.m
+++ b/MathKit/MPExpressionView.m
@@ -713,7 +713,9 @@
     if (self.functionsPopover.isShown) {
         [self.functionsPopover close];
     } else {
-        [self.functionsPopover showRelativeToRect:[sender bounds] ofView:sender preferredEdge:NSMaxYEdge];
+        [self.functionsPopover showRelativeToRect:[sender bounds]
+                                           ofView:self.functionsButton
+                                    preferredEdge:NSMaxYEdge];
     }
 }
 
diff --git a/MathKit/MPFractionFunctionLayout.m b/MathKit/MPFractionFunctionLayout.m
old mode 100644
new mode 100755
index eea7dfd..d6c8198
--- a/MathKit/MPFractionFunctionLayout.m
+++ b/MathKit/MPFractionFunctionLayout.m
@@ -11,8 +11,8 @@
 #import "MPFractionFunction.h"
 
 
-#define kFractionFunctionLineWidth 1.0
-#define kFractionFunctionHorizontalInset 2.0
+#define kFractionFunctionLineWidth 1
+#define kFractionFunctionHorizontalInset 2
 #define kFractionFunctionNominatorOffset 0
 #define kFractionFunctionDenominatorOffset 0
 
diff --git a/MathKit/MPFractionTerm.h b/MathKit/MPFractionTerm.h
old mode 100644
new mode 100755
index 69f93f1..53e7dac
--- a/MathKit/MPFractionTerm.h
+++ b/MathKit/MPFractionTerm.h
@@ -24,7 +24,7 @@
     @abstract   Represens a <code>@link
                 //apple_ref/occ/cl/MPFractionFunction@/link</code>.
  
-    @discussion A fraction is evaluating by dividing the numerator by the
+    @discussion A fraction is evaluated by dividing the numerator by the
                 denominator.
  */
 @interface MPFractionTerm : MPFunctionTerm
diff --git a/MathKit/MPSumFunction.h b/MathKit/MPSumFunction.h
old mode 100644
new mode 100755
index c25c6e3..27e01d5
--- a/MathKit/MPSumFunction.h
+++ b/MathKit/MPSumFunction.h
@@ -29,9 +29,9 @@
                 the start expression and the target expressions are included in
                 the iterations.
  
-                Each iteration the sum value is incremented by <code>1</code>. If
-                the start and target expression evaluate to the same value the
-                sum is evaluated once.
+                Each iteration the iteration value is incremented by
+                <code>1</code>. If the start and target expression evaluate to
+                the same value the sum is evaluated once.
  */
 @interface MPSumFunction : MPFunction
 
@@ -41,7 +41,7 @@
  
     @discussion The start expression must define a variable that may be used in
                 the sum expression. If the start expression does not define a
-                variable the sum function will fail on validation.
+                variable the sum function will not be evaluatable.
  */
 @property (nonatomic, strong) MPExpression *startExpression; /* Index 0 */
 
diff --git a/MathKit/MPSumFunctionTerm.m b/MathKit/MPSumFunctionTerm.m
old mode 100644
new mode 100755
index 9611e92..9acb178
--- a/MathKit/MPSumFunctionTerm.m
+++ b/MathKit/MPSumFunctionTerm.m
@@ -17,13 +17,12 @@
 - (NSDecimalNumber *)doEvaluation:(NSError *__autoreleasing *)error
 {
     MPParsedExpression *startExpression = [self expressionAtIndex:0];
-    MPParsedExpression *sumExpression = [self expressionAtIndex:2];
-    
     NSDecimalNumber *start = [startExpression evaluate:error];
     ReturnNilIfNil(start);
     MPEvaluateExpression(target, 1);
-    NSDecimalNumber *value = [NSDecimalNumber zero];
     
+    MPParsedExpression *sumExpression = [self expressionAtIndex:2];
+    NSDecimalNumber *value = [NSDecimalNumber zero];
     for (NSDecimalNumber *current = start;
          [current compare:target] <= 0;
          current = [current decimalNumberByAdding:[[NSDecimalNumber alloc] initWithInteger:1]]) {