diff --git a/src/schema/README.md b/src/schema/README.md
index 14290337c1..68be4f2a9b 100644
--- a/src/schema/README.md
+++ b/src/schema/README.md
@@ -270,7 +270,7 @@ The following functions should be defined by an interpreter:
 | `match(arg: str, pattern: str) -> bool`         | `true` if `arg` matches the regular expression `pattern` (anywhere in string)                                                                              | `match(extension, ".gz$")`                             | True if the file extension ends with `.gz`                                     |
 | `max(arg: array) -> number`                     | The largest non-`n/a` value in an array                                                                                                                    | `max(columns.onset)`                                   | The time of the last onset in an events.tsv file                               |
 | `min(arg: array) -> number`                     | The smallest non-`n/a` value in an array                                                                                                                   | `min(sidecar.SliceTiming) == 0`                        | A check that the onset of the first slice is 0s                                |
-| `sorted(arg: array) -> array`                   | The sorted values of the input array                                                                                                                       | `sorted(sidecar.VolumeTiming) == sidecar.VolumeTiming` | True if `sidecar.VolumeTiming` is sorted                                       |
+| `sorted(arg: array, method: str) -> array`      | The sorted values of the input array; defaults to type-determined sort. If method is "lexical", or "numeric" use lexical or numeric sort.                  | `sorted(sidecar.VolumeTiming) == sidecar.VolumeTiming` | True if `sidecar.VolumeTiming` is sorted                                       |
 | `substr(arg: str, start: int, end: int) -> str` | The portion of the input string spanning from start position to end position                                                                               | `substr(path, 0, length(path) - 3)`                    | `path` with the last three characters dropped                                  |
 | `type(arg: Any) -> str`                         | The name of the type, including `"array"`, `"object"`, `"null"`                                                                                            | `type(datatypes)`                                      | Returns `"array"`                                                              |
 
diff --git a/src/schema/meta/expression_tests.yaml b/src/schema/meta/expression_tests.yaml
index 8ab60a28d4..0d5d54a1f2 100644
--- a/src/schema/meta/expression_tests.yaml
+++ b/src/schema/meta/expression_tests.yaml
@@ -110,6 +110,16 @@
   result: null
 - expression: sorted([3, 2, 1])
   result: [1, 2, 3]
+- expression: sorted([1, 2, 5, 10], "lexical")
+  result: [1, 10, 2, 5]
+- expression: sorted(["1", "2", "5", "10"])
+  result: ["1", "10", "2", "5"]
+- expression: sorted(["1", "2", "5", "10"], "numeric")
+  result: ["1", "2", "5", "10"]
+- expression: sorted(["1", "2", "n/a"], "numeric")
+  result: ["1", "2", "n/a"]
+- expression: sorted(["n/a", "2", "1"], "numeric")
+  result: ["n/a", "1", "2"]
 - expression: allequal(sorted([3, 2, 1]), [1, 2, 3])
   result: true
 # Regression test. Javascript will sort lexically by default.
diff --git a/src/schema/rules/checks/events.yaml b/src/schema/rules/checks/events.yaml
index 234b9d078d..1f0f57a123 100644
--- a/src/schema/rules/checks/events.yaml
+++ b/src/schema/rules/checks/events.yaml
@@ -39,4 +39,4 @@ SortedOnsets:
     - extension == ".tsv"
   checks:
     # n/a values will likely cause false alarms if encountered. Consider alternatives.
-    - allequal(sorted(columns.onset), columns.onset)
+    - allequal(sorted(columns.onset, "numeric"), columns.onset)