diff --git a/encoding/openapi/build.go b/encoding/openapi/build.go
index eaa0df4..8387c72 100644
--- a/encoding/openapi/build.go
+++ b/encoding/openapi/build.go
@@ -15,6 +15,7 @@
 package openapi
 
 import (
+	"fmt"
 	"math"
 	"math/big"
 	"path"
@@ -612,8 +613,8 @@
 
 // string supports the following options:
 //
-// - maxLenght (Unicode codepoints)
-// - minLenght (Unicode codepoints)
+// - maxLength (Unicode codepoints)
+// - minLength (Unicode codepoints)
 // - pattern (a regexp)
 //
 // The regexp pattern is as follows, and is limited to be a  strict subset of RE2:
@@ -658,7 +659,7 @@
 			return
 		}
 		if op == cue.RegexMatchOp {
-			b.setFilter("schema", "pattern", s)
+			b.setFilter("Schema", "pattern", s)
 		} else {
 			b.setNot("pattern", s)
 		}
@@ -670,6 +671,22 @@
 	case cue.NoOp, cue.SelectorOp:
 		// TODO: determine formats from specific types.
 
+	case cue.CallOp:
+		name := fmt.Sprint(a[0])
+		field := ""
+		switch name {
+		case "strings.MinRunes":
+			field = "minLength"
+		case "strings.MaxRunes":
+			field = "maxLength"
+		default:
+			b.failf(v, "builtin %v not supported in OpenAPI", name)
+		}
+		if len(a) != 2 {
+			b.failf(v, "builtin %v may only be used with single argument", name)
+		}
+		b.setFilter("Schema", field, b.int(a[1]))
+
 	default:
 		b.failf(v, "unsupported op %v for string type", op)
 	}
diff --git a/encoding/openapi/openapi_test.go b/encoding/openapi/openapi_test.go
index d5eb721..b085f75 100644
--- a/encoding/openapi/openapi_test.go
+++ b/encoding/openapi/openapi_test.go
@@ -51,6 +51,10 @@
 		"array.json",
 		defaultConfig,
 	}, {
+		"strings.cue",
+		"strings.json",
+		defaultConfig,
+	}, {
 		"oneof.cue",
 		"oneof.json",
 		defaultConfig,
@@ -82,6 +86,9 @@
 			inst := cue.Build(load.Instances([]string{filename}, nil))[0]
 
 			b, err := Gen(inst, tc.config)
+			if err != nil {
+				t.Fatal(err)
+			}
 			var out = &bytes.Buffer{}
 			_ = json.Indent(out, b, "", "   ")
 
diff --git a/encoding/openapi/testdata/strings.cue b/encoding/openapi/testdata/strings.cue
new file mode 100644
index 0000000..f0d61fe
--- /dev/null
+++ b/encoding/openapi/testdata/strings.cue
@@ -0,0 +1,9 @@
+import "strings"
+
+MyType: {
+	myString: strings.MinRunes(1) & strings.MaxRunes(5)
+
+	myPattern: =~"foo.*bar"
+
+	myAntiPattern: !~"foo.*bar"
+}
diff --git a/encoding/openapi/testdata/strings.json b/encoding/openapi/testdata/strings.json
new file mode 100644
index 0000000..cff15f4
--- /dev/null
+++ b/encoding/openapi/testdata/strings.json
@@ -0,0 +1,34 @@
+{
+   "openapi": "3.0.0",
+   "info": {},
+   "components": {
+      "schemas": {
+         "MyType": {
+            "type": "object",
+            "required": [
+               "myString",
+               "myPattern",
+               "myAntiPattern"
+            ],
+            "properties": {
+               "myString": {
+                  "type": "string",
+                  "minLength": 1,
+                  "maxLength": 5
+               },
+               "myPattern": {
+                  "type": "string",
+                  "pattern": "foo.*bar"
+               },
+               "myAntiPattern": {
+                  "not": {
+                     "type": "string",
+                     "pattern": "foo.*bar"
+                  },
+                  "type": "string"
+               }
+            }
+         }
+      }
+   }
+}
\ No newline at end of file