diff --git a/Cargo.lock b/Cargo.lock
index 9242376..07772ad 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -120,9 +120,9 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "libc"
-version = "0.2.102"
+version = "0.2.103"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a2a5ac8f984bfcf3a823267e5fde638acc3325f6496633a5da6bb6eb2171e103"
+checksum = "dd8f7255a17a627354f321ef0055d63b898c6fb27eff628af4d1b66b7331edf6"
 
 [[package]]
 name = "linked-hash-map"
@@ -195,9 +195,9 @@ checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
 
 [[package]]
 name = "syn"
-version = "1.0.76"
+version = "1.0.80"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c6f107db402c2c2055242dbf4d2af0e69197202e9faacbef9571bbe47f5a1b84"
+checksum = "d010a1623fbd906d51d650a9916aaefc05ffa0e4053ff7fe601167f3e715d194"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/coverage_config_x86_64.json b/coverage_config_x86_64.json
index d8b86b0..ff7665f 100644
--- a/coverage_config_x86_64.json
+++ b/coverage_config_x86_64.json
@@ -1,5 +1,5 @@
 {
-  "coverage_score": 49.4,
+  "coverage_score": 49.6,
   "exclude_path": "",
   "crate_features": ""
 }
diff --git a/rust-vmm-ci b/rust-vmm-ci
index ae7db2d..7f22582 160000
--- a/rust-vmm-ci
+++ b/rust-vmm-ci
@@ -1 +1 @@
-Subproject commit ae7db2d98a071f52de3d60af9c937204b1f087a4
+Subproject commit 7f22582590b5816878e7f3f860766979cab297a0
diff --git a/src/i2c/src/main.rs b/src/i2c/src/main.rs
index b5d1bf7..768e4a0 100644
--- a/src/i2c/src/main.rs
+++ b/src/i2c/src/main.rs
@@ -97,7 +97,7 @@ impl TryFrom<&str> for AdapterConfig {
             for device_str in list[1..].iter() {
                 let addr = device_str
                     .parse::<u16>()
-                    .map_err(|_| "Invalid device addr: {}")?;
+                    .map_err(|_| "Invalid device addr")?;
                 adapter.push(addr)?;
             }
 
@@ -129,6 +129,10 @@ impl TryFrom<ArgMatches> for I2cConfiguration {
             .parse::<usize>()
             .map_err(|_| "Invalid socket_count")?;
 
+        if socket_count == 0 {
+            return Err("Socket count can't be 0".to_string());
+        }
+
         let list = cmd_args.value_of("devices").ok_or("Invalid devices list")?;
         let devices = AdapterConfig::try_from(list)?;
         Ok(I2cConfiguration {
@@ -226,41 +230,55 @@ mod tests {
         }
     }
 
-    fn get_cmd_args(name: &str, devices: &str, count: u32) -> ArgMatches {
+    fn get_cmd_args(name: &str, devices: &str, count: Option<u32>) -> ArgMatches {
+        let mut args = vec!["prog", "-s", name, "-l", devices];
         let yaml = load_yaml!("cli.yaml");
         let app = App::from(yaml);
+        let socket_count_str;
 
-        if count != 0 {
-            app.try_get_matches_from(vec![
-                "prog",
-                "-s",
-                name,
-                "-l",
-                devices,
-                "-c",
-                &count.to_string(),
-            ])
-            .unwrap()
-        } else {
-            app.try_get_matches_from(vec!["prog", "-s", name, "-l", devices])
-                .unwrap()
+        if let Some(count) = count {
+            socket_count_str = count.to_string();
+            args.extend_from_slice(&["-c", &socket_count_str]);
         }
+        app.try_get_matches_from(args).unwrap()
     }
 
     #[test]
     fn test_parse_failure() {
-        let cmd_args = get_cmd_args("vi2c.sock_failure", "1:4d", 5);
-        // TODO: Check against the actual error instead of `is_err`.
-        assert!(I2cConfiguration::try_from(cmd_args).is_err());
+        let socket_name = "vi2c.sock";
 
-        let cmd_args = get_cmd_args("vi2c.sock_duplicate", "1:4,2:32:21,5:4:23", 5);
-        // TODO: Check against the actual error instead of `is_err`.
-        assert!(I2cConfiguration::try_from(cmd_args).is_err());
+        // Invalid device list
+        let cmd_args = get_cmd_args(socket_name, "1:4d", Some(5));
+        assert_eq!(
+            I2cConfiguration::try_from(cmd_args).unwrap_err(),
+            "Invalid device addr"
+        );
+
+        // Invalid socket count
+        let cmd_args = get_cmd_args(socket_name, "1:4", Some(0));
+        assert_eq!(
+            I2cConfiguration::try_from(cmd_args).unwrap_err(),
+            "Socket count can't be 0"
+        );
+
+        // Duplicate client address: 4
+        let cmd_args = get_cmd_args(socket_name, "1:4,2:32:21,5:4:23", Some(5));
+        assert_eq!(
+            I2cConfiguration::try_from(cmd_args).unwrap_err(),
+            "Address already in use: 4"
+        );
     }
 
     #[test]
     fn test_parse_successful() {
-        let cmd_args = get_cmd_args("vi2c.sock_single", "1:4,2:32:21,5:5:23", 5);
+        let socket_name = "vi2c.sock";
+
+        // Missing socket count, default (1) should be used.
+        let cmd_args = get_cmd_args(socket_name, "1:4,2:32:21,5:5:23", None);
+        let config = I2cConfiguration::try_from(cmd_args).unwrap();
+        assert_eq!(config.socket_count, 1);
+
+        let cmd_args = get_cmd_args(socket_name, "1:4,2:32:21,5:5:23", Some(5));
         let config = I2cConfiguration::try_from(cmd_args).unwrap();
 
         let expected_devices = AdapterConfig::new_with(vec![
@@ -271,7 +289,7 @@ mod tests {
 
         let expected_config = I2cConfiguration {
             socket_count: 5,
-            socket_path: String::from("vi2c.sock_single"),
+            socket_path: String::from(socket_name),
             devices: expected_devices,
         };