diff --git a/CHANGELOG.md b/CHANGELOG.md
index d9778044..fa15a4c9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -110,6 +110,9 @@ means foot can be PGO:d in e.g. sandboxed build scripts. See
 * The sub-parameter versions of the SGR RGB color escapes (e.g
   `\E[38:2...m`) can now be used _without_ the color space ID
   parameter.
+* SGR 21 no longer disables **bold**. According to ECMA-4, SGR 21 is
+  _”double underline_”. Foot does not (yet) implement that, but that’s
+  no reason to implement a non-standard behavior.
 
 
 ### Deprecated
diff --git a/csi.c b/csi.c
index fba044bc..43d18f73 100644
--- a/csi.c
+++ b/csi.c
@@ -94,7 +94,7 @@ csi_sgr(struct terminal *term)
         case 8: term->vt.attrs.conceal = true; break;
         case 9: term->vt.attrs.strikethrough = true; break;
 
-        case 21: term->vt.attrs.bold = false; break;
+        case 21: break; /* double-underline, not implemented */
         case 22: term->vt.attrs.bold = term->vt.attrs.dim = false; break;
         case 23: term->vt.attrs.italic = false; break;
         case 24: term->vt.attrs.underline = false; break;