diff --git a/Cargo.toml b/Cargo.toml
index 7908ebd9..6055f8c4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -24,6 +24,7 @@ maintenance = { status = "actively-developed" }
 doc = false
 name = "oxipng"
 path = "src/main.rs"
+required-features = ["binary"]
 
 [dependencies]
 bit-vec = "^0.5.0"