diff --git a/cue/binop.go b/cue/binop.go
index 1e487ab..3f081a4 100644
--- a/cue/binop.go
+++ b/cue/binop.go
@@ -510,6 +510,9 @@
 			}
 			return &unification{newSrc, []evaluated{x, y}}
 
+		case *customValidator:
+			return &unification{newSrc, []evaluated{x, y}}
+
 		case *bound:
 			return &unification{newSrc, []evaluated{x, y}}
 
@@ -534,7 +537,7 @@
 			return y
 		}
 	}
-	return ctx.mkErr(src, "invalid operation %v and %v (operator not defined for custom validator)")
+	return ctx.mkErr(src, "invalid operation %v and %v (operator not defined for custom validator)", ctx.str(x), ctx.str(other))
 }
 
 func (x *customValidator) check(ctx *context, v evaluated) evaluated {
diff --git a/cue/resolve_test.go b/cue/resolve_test.go
index b1227c2..c44856d 100644
--- a/cue/resolve_test.go
+++ b/cue/resolve_test.go
@@ -738,10 +738,14 @@
 
 		b: strings.ContainsAny("c")
 		b: "dog"
+
+		c: strings.ContainsAny("d") & strings.ContainsAny("g")
+		c: "dog"
 		`,
 		out: `<0>{` +
 			`a: "after", ` +
-			`b: _|_(strings.ContainsAny ("c"):invalid value "dog" (does not satisfy strings.ContainsAny("c")))` +
+			`b: _|_(strings.ContainsAny ("c"):invalid value "dog" (does not satisfy strings.ContainsAny("c"))), ` +
+			`c: "dog"` +
 			`}`,
 	}, {
 		desc: "null coalescing",
diff --git a/cue/types.go b/cue/types.go
index ca3bc09..84dcd3e 100644
--- a/cue/types.go
+++ b/cue/types.go
@@ -1616,6 +1616,12 @@
 			a = append(a, remakeValue(v, arg))
 		}
 		op = CallOp
+	case *customValidator:
+		a = append(a, remakeValue(v, x.call))
+		for _, arg := range x.args {
+			a = append(a, remakeValue(v, arg))
+		}
+		op = CallOp
 	default:
 		a = append(a, v)
 	}