diff --git a/doc/specs/stdlib_math.md b/doc/specs/stdlib_math.md
index 5175c020a..3d6524e04 100644
--- a/doc/specs/stdlib_math.md
+++ b/doc/specs/stdlib_math.md
@@ -459,7 +459,7 @@ Experimental
 
 Elemenal function.
 
-### Description
+#### Description
 
 `rad2deg` converts phase angles from radians to degrees.