diff --git a/.circleci/config.yml b/.circleci/config.yml
index 105342f..5ca96ea 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -11,6 +11,9 @@ jobs:
       debian-version:
         type: string
         default: "buster"
+      rust-features:
+        type: string
+        default: "''"
     docker:
       - image: rust:<< parameters.rust-version >>-<< parameters.debian-version >>
     environment:
@@ -36,7 +39,7 @@ jobs:
           command: cargo build
       - run:
           name: Test
-          command: cargo test
+          command: cargo test --features=<< parameters.rust-features >>
 
   upload-coverage:
     parameters:
@@ -91,6 +94,15 @@ workflows:
             - "1.40.0"
             - "1.50.0"
             - "1.54.0"
+    - build-and-test:
+        matrix:
+          parameters:
+            rust-version:
+            - "1.50.0"
+            - "1.54.0"
+            rust-features:
+            - "'serde'"
+            - "'serde,string-only'"
     - upload-coverage:
         rust-version: "1.54.0"
         requires:
diff --git a/Cargo.toml b/Cargo.toml
index e1c7e61..e17ad59 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "bigdecimal"
-version = "0.2.2"
+version = "0.3.0"
 authors = ["Andrew Kubera"]
 description = "Arbitrary precision decimal numbers"
 documentation = "https://docs.rs/bigdecimal"
@@ -10,7 +10,7 @@ keywords = ["mathematics", "numerics", "decimal", "arbitrary-precision", "floati
 license = "MIT/Apache-2.0"
 
 [dependencies]
-num-bigint = "0.3"
+num-bigint = "0.4"
 num-integer = "0.1"
 num-traits = "0.2"
 serde = { version = "1.0", optional = true }
diff --git a/src/lib.rs b/src/lib.rs
index a59f148..8eb3dd6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1813,6 +1813,9 @@ mod bigdecimal_serde {
     use serde::{de, ser};
     use std::convert::TryFrom;
     use std::fmt;
+    use std::str::FromStr;
+    #[allow(unused_imports)]
+    use num_traits::FromPrimitive;
 
     impl ser::Serialize for BigDecimal {
         fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -1836,7 +1839,6 @@ mod bigdecimal_serde {
         where
             E: de::Error,
         {
-            use std::str::FromStr;
             BigDecimal::from_str(value).map_err(|err| E::custom(format!("{}", err)))
         }
 
@@ -1942,8 +1944,6 @@ mod bigdecimal_serde {
     #[test]
     #[cfg(not(feature = "string-only"))]
     fn test_serde_deserialize_int() {
-        use traits::FromPrimitive;
-
         let vals = vec![0, 1, 81516161, -370, -8, -99999999999];
         for n in vals {
             let expected = BigDecimal::from_i64(n).unwrap();