diff --git a/src/wireviz/templates/README.md b/src/wireviz/templates/README.md
index 358d0679..7b362fac 100644
--- a/src/wireviz/templates/README.md
+++ b/src/wireviz/templates/README.md
@@ -40,10 +40,10 @@ 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 |
-| `<!-- %{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}` |
+| `<!-- %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}` |
 
 Note that `{item}`, `{category}` and `{key}` in the description above can be
 any valid YAML key, and `{i}` is an integer representing the 1-based index of
diff --git a/src/wireviz/wv_html.py b/src/wireviz/wv_html.py
index 176d2303..4941e94a 100644
--- a/src/wireviz/wv_html.py
+++ b/src/wireviz/wv_html.py
@@ -96,7 +96,7 @@ def replacement_if_used(key: str, func: Callable[[], str]) -> None:
 
     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