diff --git a/build.go b/build.go
index 8be4a1f7..e00fe696 100644
--- a/build.go
+++ b/build.go
@@ -186,7 +186,7 @@ func Build(
 			return packit.BuildResult{}, err
 		}
 
-		mriLayer.SharedEnv.Override("GEM_PATH", strings.TrimSpace(buffer.String()))
+		mriLayer.SharedEnv.Default("GEM_PATH", strings.TrimSpace(buffer.String()))
 		mriLayer.SharedEnv.Default("MALLOC_ARENA_MAX", "2")
 
 		logger.EnvironmentVariables(mriLayer)
diff --git a/build_test.go b/build_test.go
index 021037f9..a16287e6 100644
--- a/build_test.go
+++ b/build_test.go
@@ -144,7 +144,7 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 
 		Expect(layer.SharedEnv).To(Equal(packit.Environment{
 			"MALLOC_ARENA_MAX.default": "2",
-			"GEM_PATH.override":        "/some/mri/gems/path",
+			"GEM_PATH.default":        "/some/mri/gems/path",
 		}))
 		Expect(layer.BuildEnv).To(BeEmpty())
 		Expect(layer.LaunchEnv).To(BeEmpty())