diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 28b998474..840bfecef 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -3821,8 +3821,8 @@ static RegisterPrimOp primop_parseDrvName({
     .args = {"s"},
     .doc = R"(
       Split the string *s* into a package name and version. The package
-      name is everything up to but not including the first dash followed
-      by a digit, and the version is everything following that dash. The
+      name is everything up to but not including the first dash not followed
+      by a letter, and the version is everything following that dash. The
       result is returned in a set `{ name, version }`. Thus,
       `builtins.parseDrvName "nix-0.12pre12876"` returns `{ name =
       "nix"; version = "0.12pre12876"; }`.