diff --git a/src/diagnostics.md b/src/diagnostics.md
index 2212fc79..b77e4547 100644
--- a/src/diagnostics.md
+++ b/src/diagnostics.md
@@ -182,7 +182,7 @@ replace their current content.
 The message that accompanies them should be understandable in the following
 contexts:
 
-- shown as an independent sug-diagnostic (this is the default output)
+- shown as an independent sub-diagnostic (this is the default output)
 - shown as a label pointing at the affected span (this is done automatically if
 the some heuristics for verbosity are met)
 - shown as a `help` sub-diagnostic with no content (used for cases where the