diff --git a/clippy_lints/src/utils/conf.rs b/clippy_lints/src/utils/conf.rs
index e773cc0e0250..851764edc288 100644
--- a/clippy_lints/src/utils/conf.rs
+++ b/clippy_lints/src/utils/conf.rs
@@ -151,7 +151,7 @@ define_Conf! {
     /// Lint: CYCLOMATIC_COMPLEXITY. The maximum cyclomatic complexity a function can have
     ("cyclomatic-complexity-threshold", cyclomatic_complexity_threshold, 25 => u64),
     /// Lint: DOC_MARKDOWN. The list of words this lint should not consider as identifiers needing ticks
-    ("doc-valid-idents", doc_valid_idents, ["MiB", "GiB", "TiB", "PiB", "EiB", "GitHub"] => Vec<String>),
+    ("doc-valid-idents", doc_valid_idents, ["MiB", "GiB", "TiB", "PiB", "EiB", "GitHub", "NaN"] => Vec<String>),
     /// Lint: TOO_MANY_ARGUMENTS. The maximum number of argument a function or method can have
     ("too-many-arguments-threshold", too_many_arguments_threshold, 7 => u64),
     /// Lint: TYPE_COMPLEXITY. The maximum complexity a type can have
diff --git a/tests/compile-fail/doc.rs b/tests/compile-fail/doc.rs
index d3b1c037f470..415bcb2e661f 100755
--- a/tests/compile-fail/doc.rs
+++ b/tests/compile-fail/doc.rs
@@ -46,6 +46,7 @@ fn test_emphasis() {
 /// 32kib 32Mib 32Gib 32Tib 32Pib 32Eib
 /// 32kB 32MB 32GB 32TB 32PB 32EB
 /// 32kb 32Mb 32Gb 32Tb 32Pb 32Eb
+/// NaN
 /// be_sure_we_got_to_the_end_of_it
 //~^ ERROR: you should put `be_sure_we_got_to_the_end_of_it` between ticks
 fn test_units() {