diff --git a/.github/workflows/rust.yaml b/.github/workflows/rust.yaml
index dd7b6ee4..5b4907d7 100644
--- a/.github/workflows/rust.yaml
+++ b/.github/workflows/rust.yaml
@@ -54,6 +54,10 @@ jobs:
         run: rustup install 1.80
       - run: cargo test --workspace --all-features --exclude zen-ffi --exclude zen-nodejs --exclude zen-python
       - run: cargo test --workspace --all-features --exclude zen-ffi --exclude zen-nodejs --exclude zen-python --release
+      - name: Test without arbitrary_precision
+        run: cargo test --workspace --exclude zen-ffi --exclude zen-nodejs --exclude zen-python
+      - name: Test without arbitrary_precision (release)
+        run: cargo test --workspace --exclude zen-ffi --exclude zen-nodejs --exclude zen-python --release
 
   build:
     name: cargo +${{ matrix.rust }} build
diff --git a/bindings/c/Cargo.toml b/bindings/c/Cargo.toml
index 7641efc6..ffb31ade 100644
--- a/bindings/c/Cargo.toml
+++ b/bindings/c/Cargo.toml
@@ -12,8 +12,8 @@ serde = { workspace = true }
 serde_json = { workspace = true }
 strum = { workspace = true, features = ["derive"] }
 tokio = { workspace = true, features = ["rt"] }
-zen-engine = { path = "../../core/engine" }
-zen-expression = { path = "../../core/expression" }
+zen-engine = { path = "../../core/engine", features = ["arbitrary_precision"] }
+zen-expression = { path = "../../core/expression", features = ["arbitrary_precision"] }
 zen-tmpl = { path = "../../core/template" }
 
 [lib]
diff --git a/bindings/nodejs/Cargo.toml b/bindings/nodejs/Cargo.toml
index f7488dd9..5bc273ee 100644
--- a/bindings/nodejs/Cargo.toml
+++ b/bindings/nodejs/Cargo.toml
@@ -15,8 +15,8 @@ napi-sys = "3"
 napi-derive = "3"
 tokio-util = { workspace = true, features = ["rt"] }
 serde_json = { workspace = true }
-zen-engine = { path = "../../core/engine" }
-zen-expression = { path = "../../core/expression" }
+zen-engine = { path = "../../core/engine", features = ["arbitrary_precision"] }
+zen-expression = { path = "../../core/expression", features = ["arbitrary_precision"] }
 zen-tmpl = { path = "../../core/template" }
 serde = { workspace = true, features = ["derive"] }
 json_dotpath = { workspace = true }
diff --git a/bindings/python/Cargo.toml b/bindings/python/Cargo.toml
index bd323e73..052a88b0 100644
--- a/bindings/python/Cargo.toml
+++ b/bindings/python/Cargo.toml
@@ -20,6 +20,6 @@ serde = { workspace = true }
 serde_json = { workspace = true }
 rust_decimal = { workspace = true, features = ["maths-nopanic"] }
 tokio-util = { version = "0.7", features = ["rt"] }
-zen-engine = { path = "../../core/engine" }
-zen-expression = { path = "../../core/expression" }
+zen-engine = { path = "../../core/engine", features = ["arbitrary_precision"] }
+zen-expression = { path = "../../core/expression", features = ["arbitrary_precision"] }
 zen-tmpl = { path = "../../core/template" }
diff --git a/bindings/uniffi/Cargo.toml b/bindings/uniffi/Cargo.toml
index 8315f77b..570b904c 100644
--- a/bindings/uniffi/Cargo.toml
+++ b/bindings/uniffi/Cargo.toml
@@ -15,8 +15,8 @@ path = "uniffi-bindgen.rs"
 [dependencies]
 uniffi = { version = "0.29", features = ["tokio", "cli"] }
 serde_json = { workspace = true }
-zen-engine = { path = "../../core/engine" }
-zen-expression = { path = "../../core/expression" }
+zen-engine = { path = "../../core/engine", features = ["arbitrary_precision"] }
+zen-expression = { path = "../../core/expression", features = ["arbitrary_precision"] }
 serde = { workspace = true, features = ["derive"] }
 async-trait = "0.1"
 tokio = "1.46"
diff --git a/core/engine/Cargo.toml b/core/engine/Cargo.toml
index 57baee32..22e5c4ba 100644
--- a/core/engine/Cargo.toml
+++ b/core/engine/Cargo.toml
@@ -24,9 +24,9 @@ rust_decimal = { workspace = true, features = ["maths-nopanic"] }
 fixedbitset = "0.5"
 tokio = { workspace = true, features = ["sync", "time"] }
 rquickjs = { version = "0.10", features = ["macro", "loader", "rust-alloc", "futures", "either", "properties"] }
-zen-types = { path = "../types", version = "0.53.0", default-features = false }
-zen-expression = { path = "../expression", version = "0.53.0", default-features = false, features = ["regex-deprecated"] }
-zen-tmpl = { path = "../template", version = "0.53.0", default-features = false, features = ["regex-deprecated"] }
+zen-types = { path = "../types", version = "0.53.0" }
+zen-expression = { path = "../expression", version = "0.53.0" }
+zen-tmpl = { path = "../template", version = "0.53.0" }
 nohash-hasher = { workspace = true }
 downcast-rs = { version = "2.0", features = ["std", "sync"] }
 
@@ -52,6 +52,6 @@ harness = false
 name = "engine"
 
 [features]
-default = ["arbitrary_precision"]
+default = []
 bindgen = ["rquickjs/bindgen"]
 arbitrary_precision = ["serde_json/arbitrary_precision", "zen-expression/arbitrary_precision", "zen-types/arbitrary_precision", "zen-tmpl/arbitrary_precision"]
\ No newline at end of file
diff --git a/core/expression/Cargo.toml b/core/expression/Cargo.toml
index 14858f2b..17cc30a0 100644
--- a/core/expression/Cargo.toml
+++ b/core/expression/Cargo.toml
@@ -30,7 +30,7 @@ strsim = "0.11"
 iana-time-zone = "0.1"
 
 zen-macros = { path = "../macros", version = "0.53.0" }
-zen-types = { path = "../types", version = "0.53.0", default-features = false }
+zen-types = { path = "../types", version = "0.53.0" }
 
 [dev-dependencies]
 criterion = { workspace = true }
@@ -41,7 +41,7 @@ serde_json5 = "0.2"
 recursive = { workspace = true }
 
 [features]
-default = ["regex-deprecated", "arbitrary_precision"]
+default = ["regex-deprecated"]
 regex-lite = ["dep:regex-lite"]
 regex-deprecated = ["dep:regex"]
 arbitrary_precision = ["serde_json/arbitrary_precision", "zen-types/arbitrary_precision"]
diff --git a/core/template/Cargo.toml b/core/template/Cargo.toml
index c825e00c..bffc9830 100644
--- a/core/template/Cargo.toml
+++ b/core/template/Cargo.toml
@@ -8,13 +8,13 @@ edition = "2021"
 repository = "https://github.com/gorules/zen.git"
 
 [dependencies]
-zen-expression = { path = "../expression", version = "0.53.0", default-features = false }
+zen-expression = { path = "../expression", version = "0.53.0" }
 thiserror = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 
 [features]
-default = ["regex-deprecated", "arbitrary_precision"]
+default = ["regex-deprecated"]
 
 regex-lite = ["zen-expression/regex-lite"]
 regex-deprecated = ["zen-expression/regex-deprecated"]
diff --git a/core/types/Cargo.toml b/core/types/Cargo.toml
index e3b1b0d4..2da2fa56 100644
--- a/core/types/Cargo.toml
+++ b/core/types/Cargo.toml
@@ -15,5 +15,5 @@ thiserror = { workspace = true }
 nohash-hasher = { workspace = true }
 
 [features]
-default = ["arbitrary_precision"]
+default = []
 arbitrary_precision = ["serde_json/arbitrary_precision"]
diff --git a/core/types/build.rs b/core/types/build.rs
new file mode 100644
index 00000000..ae4a0310
--- /dev/null
+++ b/core/types/build.rs
@@ -0,0 +1,7 @@
+fn main() {
+    #[cfg(not(feature = "arbitrary_precision"))]
+    println!("cargo:warning=zen: arbitrary_precision is now opt-in across all zen crates \
+        (zen-engine, zen-expression, zen-types). \
+        If you rely on precise decimal handling, add features = [\"arbitrary_precision\"]. \
+        See CHANGELOG for details.");
+}