diff --git a/src/bindgen/cargo/cargo.rs b/src/bindgen/cargo/cargo.rs
index fa9d6c222..942de9b2c 100644
--- a/src/bindgen/cargo/cargo.rs
+++ b/src/bindgen/cargo/cargo.rs
@@ -13,10 +13,10 @@ use bindgen::error::Error;
 use bindgen::ir::Cfg;
 
 /// Parse a dependency string used in Cargo.lock
-fn parse_dep_string(dep_string: &str) -> (&str, &str) {
+fn parse_dep_string(dep_string: &str) -> (&str, Option<&str>) {
     let split: Vec<&str> = dep_string.split_whitespace().collect();
 
-    (split[0], split[1])
+    (split[0], split.get(1).cloned())
 }
 
 /// A collection of metadata for a library from cargo.
@@ -99,14 +99,25 @@ impl Cargo {
 
         // Find the dependencies listing in the lockfile
         if let Some(ref root) = lock.root {
-            if root.name == package.name && root.version == package.version {
+            // If the version is not on the lockfile then it shouldn't be
+            // ambiguous.
+            if root.name == package.name
+                && package
+                    .version
+                    .as_ref()
+                    .map_or(true, |v| *v == root.version)
+            {
                 dependencies = root.dependencies.as_ref();
             }
         }
         if dependencies.is_none() {
             if let Some(ref lock_packages) = lock.package {
                 for lock_package in lock_packages {
-                    if lock_package.name == package.name && lock_package.version == package.version
+                    if lock_package.name == package.name
+                        && package
+                            .version
+                            .as_ref()
+                            .map_or(true, |v| *v == lock_package.version)
                     {
                         dependencies = lock_package.dependencies.as_ref();
                         break;
@@ -134,7 +145,7 @@ impl Cargo {
 
                 let package_ref = PackageRef {
                     name: dep_name.to_owned(),
-                    version: dep_version.to_owned(),
+                    version: dep_version.map(|v| v.to_owned()),
                 };
 
                 (package_ref, cfg)
@@ -202,7 +213,7 @@ impl Cargo {
         cargo_expand::expand(
             &self.manifest_path,
             &package.name,
-            &package.version,
+            package.version.as_ref().map(|v| &**v),
             self.clean,
             expand_all_features,
             expand_default_features,
diff --git a/src/bindgen/cargo/cargo_expand.rs b/src/bindgen/cargo/cargo_expand.rs
index 86e45156f..469722322 100644
--- a/src/bindgen/cargo/cargo_expand.rs
+++ b/src/bindgen/cargo/cargo_expand.rs
@@ -60,7 +60,7 @@ impl error::Error for Error {
 pub fn expand(
     manifest_path: &Path,
     crate_name: &str,
-    version: &str,
+    version: Option<&str>,
     use_tempdir: bool,
     expand_all_features: bool,
     expand_default_features: bool,
@@ -109,7 +109,12 @@ pub fn expand(
         cmd.arg("--no-default-features");
     }
     cmd.arg("-p");
-    cmd.arg(&format!("{}:{}", crate_name, version));
+    let mut package = crate_name.to_owned();
+    if let Some(version) = version {
+        package.push_str(":");
+        package.push_str(version);
+    }
+    cmd.arg(&package);
     cmd.arg("--verbose");
     cmd.arg("--");
     cmd.arg("-Z");
diff --git a/src/bindgen/cargo/cargo_lock.rs b/src/bindgen/cargo/cargo_lock.rs
index bc5907117..9d68a3b2f 100644
--- a/src/bindgen/cargo/cargo_lock.rs
+++ b/src/bindgen/cargo/cargo_lock.rs
@@ -39,7 +39,7 @@ pub struct Lock {
 pub struct Package {
     pub name: String,
     pub version: String,
-    /// A list of dependencies formatted like "NAME VERSION REGISTRY-OPT"
+    /// A list of dependencies formatted like "NAME VERSION-OPT REGISTRY-OPT"
     pub dependencies: Option<Vec<String>>,
 }
 
diff --git a/src/bindgen/cargo/cargo_metadata.rs b/src/bindgen/cargo/cargo_metadata.rs
index 681acc8d3..2745029e9 100644
--- a/src/bindgen/cargo/cargo_metadata.rs
+++ b/src/bindgen/cargo/cargo_metadata.rs
@@ -36,7 +36,7 @@ pub struct Metadata {
 #[derive(Clone, Debug, Hash, Eq, PartialEq, Serialize, Deserialize)]
 pub struct PackageRef {
     pub name: String,
-    pub version: String,
+    pub version: Option<String>,
 }
 
 #[derive(Clone, Deserialize, Debug)]
diff --git a/src/bindgen/parser.rs b/src/bindgen/parser.rs
index 67b3539cc..9f71e2874 100644
--- a/src/bindgen/parser.rs
+++ b/src/bindgen/parser.rs
@@ -52,7 +52,7 @@ pub fn parse_src(src_file: &FilePath, config: &Config) -> ParseResult {
 
     let pkg_ref = PackageRef {
         name: mod_name.to_owned(),
-        version: "0.0.0".to_owned(),
+        version: None,
     };
 
     context.parse_mod(&pkg_ref, src_file)?;
diff --git a/tests/expectations/both/expand_dep_v2.c b/tests/expectations/both/expand_dep_v2.c
new file mode 100644
index 000000000..401228965
--- /dev/null
+++ b/tests/expectations/both/expand_dep_v2.c
@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct dep_struct {
+  uint32_t x;
+  double y;
+} dep_struct;
+
+uint32_t get_x(const dep_struct *dep_struct);
diff --git a/tests/expectations/both/expand_dep_v2.compat.c b/tests/expectations/both/expand_dep_v2.compat.c
new file mode 100644
index 000000000..056089ef0
--- /dev/null
+++ b/tests/expectations/both/expand_dep_v2.compat.c
@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct dep_struct {
+  uint32_t x;
+  double y;
+} dep_struct;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+uint32_t get_x(const dep_struct *dep_struct);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus
diff --git a/tests/expectations/expand_dep_v2.c b/tests/expectations/expand_dep_v2.c
new file mode 100644
index 000000000..3d2cf8e14
--- /dev/null
+++ b/tests/expectations/expand_dep_v2.c
@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+  uint32_t x;
+  double y;
+} dep_struct;
+
+uint32_t get_x(const dep_struct *dep_struct);
diff --git a/tests/expectations/expand_dep_v2.compat.c b/tests/expectations/expand_dep_v2.compat.c
new file mode 100644
index 000000000..4dc7fb377
--- /dev/null
+++ b/tests/expectations/expand_dep_v2.compat.c
@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+  uint32_t x;
+  double y;
+} dep_struct;
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+uint32_t get_x(const dep_struct *dep_struct);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus
diff --git a/tests/expectations/expand_dep_v2.cpp b/tests/expectations/expand_dep_v2.cpp
new file mode 100644
index 000000000..f03f098b1
--- /dev/null
+++ b/tests/expectations/expand_dep_v2.cpp
@@ -0,0 +1,15 @@
+#include <cstdarg>
+#include <cstdint>
+#include <cstdlib>
+#include <new>
+
+struct dep_struct {
+  uint32_t x;
+  double y;
+};
+
+extern "C" {
+
+uint32_t get_x(const dep_struct *dep_struct);
+
+} // extern "C"
diff --git a/tests/expectations/tag/expand_dep_v2.c b/tests/expectations/tag/expand_dep_v2.c
new file mode 100644
index 000000000..45fcba665
--- /dev/null
+++ b/tests/expectations/tag/expand_dep_v2.c
@@ -0,0 +1,11 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+struct dep_struct {
+  uint32_t x;
+  double y;
+};
+
+uint32_t get_x(const struct dep_struct *dep_struct);
diff --git a/tests/expectations/tag/expand_dep_v2.compat.c b/tests/expectations/tag/expand_dep_v2.compat.c
new file mode 100644
index 000000000..344af6468
--- /dev/null
+++ b/tests/expectations/tag/expand_dep_v2.compat.c
@@ -0,0 +1,19 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+struct dep_struct {
+  uint32_t x;
+  double y;
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+uint32_t get_x(const struct dep_struct *dep_struct);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus
diff --git a/tests/rust/expand_dep_v2/Cargo.lock b/tests/rust/expand_dep_v2/Cargo.lock
new file mode 100644
index 000000000..5e12ed603
--- /dev/null
+++ b/tests/rust/expand_dep_v2/Cargo.lock
@@ -0,0 +1,24 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "dep"
+version = "0.1.0"
+
+[[package]]
+name = "dep"
+version = "0.2.0"
+
+[[package]]
+name = "expand-dep"
+version = "0.1.0"
+dependencies = [
+ "dep 0.1.0",
+]
+
+[[package]]
+name = "expand-dep-2"
+version = "0.2.0"
+dependencies = [
+ "dep 0.2.0",
+ "expand-dep",
+]
diff --git a/tests/rust/expand_dep_v2/Cargo.toml b/tests/rust/expand_dep_v2/Cargo.toml
new file mode 100644
index 000000000..fbfeb8a09
--- /dev/null
+++ b/tests/rust/expand_dep_v2/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "expand-dep-2"
+version = "0.2.0"
+authors = ["cbindgen"]
+edition = "2018"
+
+[dependencies]
+expand-dep = { path = "../expand_dep" }
+dep = { path = "dep_v2" }
diff --git a/tests/rust/expand_dep_v2/cbindgen.toml b/tests/rust/expand_dep_v2/cbindgen.toml
new file mode 100644
index 000000000..b6e180a04
--- /dev/null
+++ b/tests/rust/expand_dep_v2/cbindgen.toml
@@ -0,0 +1,6 @@
+[parse]
+parse_deps = true
+include = ["dep"]
+
+[parse.expand]
+crates = ["expand-dep"]
diff --git a/tests/rust/expand_dep_v2/dep/Cargo.toml b/tests/rust/expand_dep_v2/dep/Cargo.toml
new file mode 100644
index 000000000..1cc8d6241
--- /dev/null
+++ b/tests/rust/expand_dep_v2/dep/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "dep"
+version = "0.1.0"
+authors = ["cbindgen"]
+edition = "2018"
+
+[dependencies]
diff --git a/tests/rust/expand_dep_v2/dep/src/lib.rs b/tests/rust/expand_dep_v2/dep/src/lib.rs
new file mode 100644
index 000000000..7253c5770
--- /dev/null
+++ b/tests/rust/expand_dep_v2/dep/src/lib.rs
@@ -0,0 +1,5 @@
+#[repr(C)]
+pub struct dep_struct {
+    pub x: u32,
+    pub y: f64,
+}
diff --git a/tests/rust/expand_dep_v2/dep_v2/Cargo.toml b/tests/rust/expand_dep_v2/dep_v2/Cargo.toml
new file mode 100644
index 000000000..fe52e954c
--- /dev/null
+++ b/tests/rust/expand_dep_v2/dep_v2/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "dep"
+version = "0.2.0"
+authors = ["cbindgen"]
+edition = "2018"
+
+[dependencies]
diff --git a/tests/rust/expand_dep_v2/dep_v2/src/lib.rs b/tests/rust/expand_dep_v2/dep_v2/src/lib.rs
new file mode 100644
index 000000000..7253c5770
--- /dev/null
+++ b/tests/rust/expand_dep_v2/dep_v2/src/lib.rs
@@ -0,0 +1,5 @@
+#[repr(C)]
+pub struct dep_struct {
+    pub x: u32,
+    pub y: f64,
+}
diff --git a/tests/rust/expand_dep_v2/src/lib.rs b/tests/rust/expand_dep_v2/src/lib.rs
new file mode 100644
index 000000000..639678d07
--- /dev/null
+++ b/tests/rust/expand_dep_v2/src/lib.rs
@@ -0,0 +1,6 @@
+use dep::dep_struct;
+
+#[no_mangle]
+pub unsafe extern "C" fn get_x(dep_struct: *const dep_struct) -> u32 {
+    dep_struct.read().x
+}