diff --git a/Headers/CoreGraphics/CGAffineTransform.h b/Headers/CoreGraphics/CGAffineTransform.h

index f023380..218f967 100644

--- a/Headers/CoreGraphics/CGAffineTransform.h

+++ b/Headers/CoreGraphics/CGAffineTransform.h

@@ -42,7 +42,7 @@ typedef struct CGAffineTransform

 /* Constants */

-const CGAffineTransform CGAffineTransformIdentity;

+extern const CGAffineTransform CGAffineTransformIdentity;

 /* Functions */

diff --git a/Source/OpalText/OPFont.h b/Source/OpalText/OPFont.h

index 75c9b33..4ef9cc0 100644

--- a/Source/OpalText/OPFont.h

+++ b/Source/OpalText/OPFont.h

@@ -72,7 +72,7 @@ typedef enum _OPFontRenderingMode

   OPFontAntialiasedIntegerAdvancementsRenderingMode

 } OPFontRenderingMode;

-const CGFloat *OPFontIdentityMatrix;

+extern const CGFloat *OPFontIdentityMatrix;

 /**

diff --git a/Source/OpalText/OPFontDescriptor.h b/Source/OpalText/OPFontDescriptor.h

index 159771d..8e3874e 100644

--- a/Source/OpalText/OPFontDescriptor.h

+++ b/Source/OpalText/OPFontDescriptor.h

@@ -75,33 +75,33 @@ enum _OPFontTrait

 // FIXME: Document these with the value type

-NSString *OPFontFamilyAttribute;

-NSString *OPFontNameAttribute;

-NSString *OPFontFaceAttribute;

-NSString *OPFontSizeAttribute; 

-NSString *OPFontVisibleNameAttribute; 

-NSString *OPFontColorAttribute;

+extern NSString *OPFontFamilyAttribute;

+extern NSString *OPFontNameAttribute;

+extern NSString *OPFontFaceAttribute;

+extern NSString *OPFontSizeAttribute; 

+extern NSString *OPFontVisibleNameAttribute; 

+extern NSString *OPFontColorAttribute;

 /**

  * NOTE: OPFontMatrixAttribute is a NSAffineTransform, unlike kCTFontMatrixAttribute which 

  * is an NSData containing a CGAffineTransform struct.

  */

-NSString *OPFontMatrixAttribute;

-NSString *OPFontVariationAttribute;

-NSString *OPFontCharacterSetAttribute;

-NSString *OPFontCascadeListAttribute;

-NSString *OPFontTraitsAttribute;

-NSString *OPFontFixedAdvanceAttribute;

-

-NSString *OPFontSymbolicTrait;

-NSString *OPFontWeightTrait;

-NSString *OPFontWidthTrait;

-NSString *OPFontSlantTrait;

-

-NSString *OPFontVariationAxisIdentifierKey;

-NSString *OPFontVariationAxisMinimumValueKey;

-NSString *OPFontVariationAxisMaximumValueKey;

-NSString *OPFontVariationAxisDefaultValueKey;

-NSString *OPFontVariationAxisNameKey;

+extern NSString *OPFontMatrixAttribute;

+extern NSString *OPFontVariationAttribute;

+extern NSString *OPFontCharacterSetAttribute;

+extern NSString *OPFontCascadeListAttribute;

+extern NSString *OPFontTraitsAttribute;

+extern NSString *OPFontFixedAdvanceAttribute;

+

+extern NSString *OPFontSymbolicTrait;

+extern NSString *OPFontWeightTrait;

+extern NSString *OPFontWidthTrait;

+extern NSString *OPFontSlantTrait;

+

+extern NSString *OPFontVariationAxisIdentifierKey;

+extern NSString *OPFontVariationAxisMinimumValueKey;

+extern NSString *OPFontVariationAxisMaximumValueKey;

+extern NSString *OPFontVariationAxisDefaultValueKey;

+extern NSString *OPFontVariationAxisNameKey;

 @interface OPFontDescriptor : NSObject <NSCopying>

 {

diff --git a/Source/OpalText/OPFontDescriptor.m b/Source/OpalText/OPFontDescriptor.m

index 967f70b..1c06aae 100644

--- a/Source/OpalText/OPFontDescriptor.m

+++ b/Source/OpalText/OPFontDescriptor.m

@@ -39,6 +39,33 @@

 #include <CoreText/CTFontDescriptor.h>

 #import "OPFontDescriptor.h"

+NSString *OPFontFamilyAttribute;

+NSString *OPFontNameAttribute;

+NSString *OPFontFaceAttribute;

+NSString *OPFontSizeAttribute;

+NSString *OPFontVisibleNameAttribute;

+NSString *OPFontColorAttribute;

+/**

+ * NOTE: OPFontMatrixAttribute is a NSAffineTransform, unlike kCTFontMatrixAttribute which 

+ * is an NSData containing a CGAffineTransform struct.

+ */

+NSString *OPFontMatrixAttribute;

+NSString *OPFontVariationAttribute;

+NSString *OPFontCharacterSetAttribute;

+NSString *OPFontCascadeListAttribute;

+NSString *OPFontTraitsAttribute;                                                        

+NSString *OPFontFixedAdvanceAttribute;

+

+NSString *OPFontSymbolicTrait;

+NSString *OPFontWeightTrait;

+NSString *OPFontWidthTrait;

+NSString *OPFontSlantTrait;

+

+NSString *OPFontVariationAxisIdentifierKey;

+NSString *OPFontVariationAxisMinimumValueKey;

+NSString *OPFontVariationAxisMaximumValueKey;

+NSString *OPFontVariationAxisDefaultValueKey;

+NSString *OPFontVariationAxisNameKey;

 @implementation OPFontDescriptor