diff --git a/Source/NSBitmapImageRep.m b/Source/NSBitmapImageRep.m
index 639d7458f..639c1e4eb 100644
--- a/Source/NSBitmapImageRep.m
+++ b/Source/NSBitmapImageRep.m
@@ -1362,7 +1362,7 @@ _set_bit_value(unsigned char *base, long msb_off, int bit_width,
   if (image == 0)
     {
       [NSException raise: NSTIFFException 
-		   format: @"Opening data stream for writting"];
+		   format: @"Opening data stream for writing"];
     }
 
   while ((rep = [enumerator nextObject]) != nil)
@@ -1423,7 +1423,7 @@ _set_bit_value(unsigned char *base, long msb_off, int bit_width,
   if (image == 0)
     {
       [NSException raise: NSTIFFException 
-		   format: @"Opening data stream for writting"];
+		   format: @"Opening data stream for writing"];
     }
 
   while ((rep = [enumerator nextObject]) != nil)