diff --git a/include/freetype/freetype.h b/include/freetype/freetype.h
index d3ea3f0..cb31c3c 100644
--- a/include/freetype/freetype.h
+++ b/include/freetype/freetype.h
@@ -522,13 +522,13 @@
    *   size.
    *
    * @note:
-   *   An @FT_Face has one _active_ @FT_Size object that is used by functions
-   *   like @FT_Load_Glyph to determine the scaling transformation that in
-   *   turn is used to load and hint glyphs and metrics.
+   *   An @FT_Face has one _active_ `FT_Size` object that is used by
+   *   functions like @FT_Load_Glyph to determine the scaling transformation
+   *   that in turn is used to load and hint glyphs and metrics.
    *
    *   You can use @FT_Set_Char_Size, @FT_Set_Pixel_Sizes, @FT_Request_Size
    *   or even @FT_Select_Size to change the content (i.e., the scaling
-   *   values) of the active @FT_Size.
+   *   values) of the active `FT_Size`.
    *
    *   You can use @FT_New_Size to create additional size objects for a given
    *   @FT_Face, but they won't be used by other functions until you activate
@@ -2702,8 +2702,8 @@
    *   'https://www.freetype.org/freetype2/docs/glyphs/glyphs-2.html'.
    *
    *   Contrary to @FT_Set_Char_Size, this function doesn't have special code
-   *   to normalize zero-valued widths, heights, or resolutions (which lead
-   *   to errors in most cases).
+   *   to normalize zero-valued widths, heights, or resolutions, which are
+   *   treated as @FT_LOAD_NO_SCALE.
    *
    *   Don't use this function if you are using the FreeType cache API.
    */
@@ -2819,7 +2819,7 @@
    *
    *   load_flags ::
    *     A flag indicating what to load for this glyph.  The @FT_LOAD_XXX
-   *     constants can be used to control the glyph loading process (e.g.,
+   *     flags can be used to control the glyph loading process (e.g.,
    *     whether the outline should be scaled, whether to load bitmaps or
    *     not, whether to hint the outline, etc).
    *
@@ -2827,6 +2827,9 @@
    *   FreeType error code.  0~means success.
    *
    * @note:
+   *   For proper scaling and hinting, the active @FT_Size object owned by
+   *   the face has to be meaningfully non-trivially initialized by
+   *   calling @FT_Set_Char_Size before this function, for example.
    *   The loaded glyph may be transformed.  See @FT_Set_Transform for the
    *   details.
    *
@@ -2918,6 +2921,8 @@
    *
    *   FT_LOAD_NO_SCALE ::
    *     Don't scale the loaded outline glyph but keep it in font units.
+   *     This flag is also assumed if @FT_Size owned by the face was not
+   *     properly initialized.
    *
    *     This flag implies @FT_LOAD_NO_HINTING and @FT_LOAD_NO_BITMAP, and
    *     unsets @FT_LOAD_RENDER.
@@ -3410,7 +3415,7 @@
    *     @FT_Render_Mode for a list of possible values.
    *
    *     If @FT_RENDER_MODE_NORMAL is used, a previous call of @FT_Load_Glyph
-   *     with flag @FT_LOAD_COLOR makes FT_Render_Glyph provide a default
+   *     with flag @FT_LOAD_COLOR makes `FT_Render_Glyph` provide a default
    *     blending of colored glyph layers associated with the current glyph
    *     slot (provided the font contains such layers) instead of rendering
    *     the glyph slot's outline.  This is an experimental feature; see
@@ -3420,9 +3425,6 @@
    *   FreeType error code.  0~means success.
    *
    * @note:
-   *   To get meaningful results, font scaling values must be set with
-   *   functions like @FT_Set_Char_Size before calling `FT_Render_Glyph`.
-   *
    *   When FreeType outputs a bitmap of a glyph, it really outputs an alpha
    *   coverage map.  If a pixel is completely covered by a filled-in
    *   outline, the bitmap contains 0xFF at that pixel, meaning that
diff --git a/src/base/ftobjs.c b/src/base/ftobjs.c
index 18de2f7..4f5e7d4 100644
--- a/src/base/ftobjs.c
+++ b/src/base/ftobjs.c
@@ -858,6 +858,11 @@
     library = driver->root.library;
     hinter  = library->auto_hinter;
 
+    /* undefined scale means no scale */
+    if ( face->size->metrics.x_ppem == 0 ||
+         face->size->metrics.y_ppem == 0 )
+      load_flags |= FT_LOAD_NO_SCALE;
+
     /* resolve load flags dependencies */
 
     if ( load_flags & FT_LOAD_NO_RECURSE )