diff --git a/spack/package.py b/spack/package.py
index 8c05620c..54f2348e 100644
--- a/spack/package.py
+++ b/spack/package.py
@@ -86,9 +86,9 @@ def url_for_version(self, version):
     )
     variant(
         "ipolates",
-        default="0",
-        description="Use to interpolate to new grids (0 = OFF, 1 = ip, 3 = ip2)",
-        values=("0", "1", "3"),
+        default=False,
+        description="Use to interpolate to new grids",
+        when="@3.3:",
     )
     variant(
         "spectral", default=False, description="Spectral interpolation in -new_grid", when="@:3.1"
@@ -151,9 +151,8 @@ def url_for_version(self, version):
     conflicts("+openmp", when="%apple-clang")
 
     depends_on("wget", type=("build"), when="@:3.1 +netcdf4")
-    depends_on("ip@:3", when="@3.2 ipolates=1")
-    depends_on("ip2", when="@3.2 ipolates=3")
-    depends_on("ip@5.1:", when="@develop ipolates=1")
+    depends_on("ip@:3", when="@3.2 +ipolates")
+    depends_on("ip@5.1:", when="@develop +ipolates")
     depends_on("libaec@1.0.6:", when="@3.2: +aec")
     depends_on("netcdf-c", when="@3.2: +netcdf4")
     depends_on("jasper@:2", when="@3.2: +jasper")