diff --git a/src/ast/intrinsic.cc b/src/ast/intrinsic.cc
index ce3d692215..14fdeefe54 100644
--- a/src/ast/intrinsic.cc
+++ b/src/ast/intrinsic.cc
@@ -18,6 +18,8 @@ namespace tint {
 namespace ast {
 
 std::ostream& operator<<(std::ostream& out, Intrinsic i) {
+  /// The emitted name matches the spelling in the WGSL spec.
+  /// including case.
   switch (i) {
     case Intrinsic::kAbs:
       out << "abs";
diff --git a/src/ast/intrinsic.h b/src/ast/intrinsic.h
index 60fc4acae3..9eb160048f 100644
--- a/src/ast/intrinsic.h
+++ b/src/ast/intrinsic.h
@@ -93,6 +93,8 @@ enum class Intrinsic {
   kTrunc
 };
 
+/// Emits the name of the intrinsic function. The spelling,
+/// including case, matches the name in the WGSL spec.
 std::ostream& operator<<(std::ostream& out, Intrinsic i);
 
 namespace intrinsic {