diff --git a/go.mod b/go.mod
index 6eea393..5409145 100644
--- a/go.mod
+++ b/go.mod
@@ -1,5 +1,7 @@
 module github.com/alexflint/go-scalar
 
+go 1.15
+
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect