diff --git a/helper/resource/id.go b/helper/resource/id.go
index 1cde67c1aa..44949550e7 100644
--- a/helper/resource/id.go
+++ b/helper/resource/id.go
@@ -18,6 +18,11 @@ func UniqueId() string {
 	return PrefixedUniqueId(UniqueIdPrefix)
 }
 
+// UniqueIDSuffixLength is the string length of the suffix generated by
+// PrefixedUniqueId. This can be used by length validation functions to
+// ensure prefixes are the correct length for the target field.
+const UniqueIDSuffixLength = 26
+
 // Helper for a resource to generate a unique identifier w/ given prefix
 //
 // After the prefix, the ID consists of an incrementing 26 digit value (to match
diff --git a/helper/resource/id_test.go b/helper/resource/id_test.go
index 7e5f27bfb7..f1560dab13 100644
--- a/helper/resource/id_test.go
+++ b/helper/resource/id_test.go
@@ -15,8 +15,6 @@ func TestUniqueId(t *testing.T) {
 		return rest[:18], rest[18:]
 	}
 
-	const prefix = "terraform-"
-
 	iterations := 10000
 	ids := make(map[string]struct{})
 	var id, lastId string
@@ -27,14 +25,14 @@ func TestUniqueId(t *testing.T) {
 			t.Fatalf("Got duplicated id! %s", id)
 		}
 
-		if !strings.HasPrefix(id, prefix) {
+		if !strings.HasPrefix(id, UniqueIdPrefix) {
 			t.Fatalf("Unique ID didn't have terraform- prefix! %s", id)
 		}
 
-		rest := strings.TrimPrefix(id, prefix)
+		rest := strings.TrimPrefix(id, UniqueIdPrefix)
 
-		if len(rest) != 26 {
-			t.Fatalf("Post-prefix part has wrong length! %s", rest)
+		if len(rest) != UniqueIDSuffixLength {
+			t.Fatalf("PrefixedUniqueId is out of sync with UniqueIDSuffixLength, post-prefix part has wrong length! %s", rest)
 		}
 
 		timestamp, increment := split(rest)
@@ -58,8 +56,8 @@ func TestUniqueId(t *testing.T) {
 	id1 := UniqueId()
 	time.Sleep(time.Millisecond)
 	id2 := UniqueId()
-	timestamp1, _ := split(strings.TrimPrefix(id1, prefix))
-	timestamp2, _ := split(strings.TrimPrefix(id2, prefix))
+	timestamp1, _ := split(strings.TrimPrefix(id1, UniqueIdPrefix))
+	timestamp2, _ := split(strings.TrimPrefix(id2, UniqueIdPrefix))
 
 	if timestamp1 == timestamp2 {
 		t.Fatalf("Timestamp part should update at least once a millisecond %s %s",