diff --git a/package.json b/package.json
index 2de3702..4801001 100644
--- a/package.json
+++ b/package.json
@@ -36,7 +36,7 @@
   "dependencies": {
     "d3-array": "1.2.0 - 2",
     "d3-format": "1",
-    "d3-interpolate": "1",
+    "d3-interpolate": "^1.2.0",
     "d3-time": "1",
     "d3-time-format": "2"
   },