diff --git a/src/wireviz/templates/README.md b/src/wireviz/templates/README.md
index 41f9e0a..4b870c8 100644
--- a/src/wireviz/templates/README.md
+++ b/src/wireviz/templates/README.md
@@ -39,7 +39,7 @@ Note that there must be one single space between `--` and `%` at both ends.
 | `<!-- %sheet_current% -->` | `1` (multi-page documents not yet supported) |
 | `<!-- %sheet_total% -->`   | `1` (multi-page documents not yet supported) |
 | `<!-- %diagram% -->`       | Embedded SVG diagram as valid HTML |
-| `<!-- %diagram_png_base64% -->` | Embedded base64 encoded PNG diagram as URI |
+| `<!-- %diagram_png_b64% -->` | Embedded base64 encoded PNG diagram as URI |
 | `<!-- %{item}% -->`             | String or numeric value of `metadata.{item}` |
 | `<!-- %{item}_{i}% -->`         | Category number `{i}` within dict value of `metadata.{item}` |
 | `<!-- %{item}_{i}_{key}% -->`   | Value of `metadata.{item}.{category}.{key}` |
diff --git a/src/wireviz/wv_output.py b/src/wireviz/wv_output.py
index 57ce2ad..2b587fc 100644
--- a/src/wireviz/wv_output.py
+++ b/src/wireviz/wv_output.py
@@ -154,7 +154,7 @@ def generate_html_output(
 
     replacement_if_used("<!-- %diagram% -->", svgdata)
     replacement_if_used(
-        "<!-- %diagram_png_base64% -->", lambda: data_URI_base64(f"{filename}.png")
+        "<!-- %diagram_png_b64% -->", lambda: data_URI_base64(f"{filename}.png")
     )
 
     # prepare metadata replacements