diff --git a/libpng-manual.txt b/libpng-manual.txt
index 7ff1b675b..41e0b9600 100644
--- a/libpng-manual.txt
+++ b/libpng-manual.txt
@@ -1693,7 +1693,7 @@ is called to insert filler bytes, either before or after each RGB triplet.
 16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
 byte of the color value first, unless png_set_scale_16() is called to
 transform it to regular RGB RGB triplets, or png_set_filler_16() or
-png_set_add alpha_16() is called to insert trwo filler bytes, either before
+png_set_add alpha_16() is called to insert two filler bytes, either before
 or after each RRGGBB triplet.  Similarly, 8-bit or 16-bit grayscale data
 can be modified with png_set_filler_16(), png_set_add_alpha_16(),
 png_set_strip_16(), or png_set_scale_16().  Note that png_set_filler_16()
diff --git a/libpng.3 b/libpng.3
index 82802642d..ae1e2bcf1 100644
--- a/libpng.3
+++ b/libpng.3
@@ -2205,7 +2205,7 @@ is called to insert filler bytes, either before or after each RGB triplet.
 16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
 byte of the color value first, unless png_set_scale_16() is called to
 transform it to regular RGB RGB triplets, or png_set_filler_16() or
-png_set_add alpha_16() is called to insert trwo filler bytes, either before
+png_set_add alpha_16() is called to insert two filler bytes, either before
 or after each RRGGBB triplet.  Similarly, 8-bit or 16-bit grayscale data
 can be modified with png_set_filler_16(), png_set_add_alpha_16(),
 png_set_strip_16(), or png_set_scale_16().  Note that png_set_filler_16()