diff --git a/paho-mqtt-sys/build.rs b/paho-mqtt-sys/build.rs
index f185b01..6deeadc 100644
--- a/paho-mqtt-sys/build.rs
+++ b/paho-mqtt-sys/build.rs
@@ -240,7 +240,26 @@ mod build {
     // but it only seems to set a variable for the path to the include files.
     // We assume the directory above that one is the SSL root.
     fn openssl_root_dir() -> Option<String> {
-        env::var("DEP_OPENSSL_INCLUDE").ok().and_then(|path| {
+        use std::ffi::OsString;
+
+        fn env_inner(name: &str) -> Option<OsString> {
+            let var = env::var_os(name);
+            println!("cargo:rerun-if-env-changed={}", name);
+
+            match var {
+                Some(ref v) => println!("{} = {}", name, v.to_string_lossy()),
+                None => println!("{} unset", name),
+            }
+
+            var
+        }
+        fn env(name: &str) -> Option<OsString> {
+            let prefix = env::var("TARGET").unwrap().to_uppercase().replace('-', "_");
+            let prefixed = format!("{}_{}", prefix, name);
+            env_inner(&prefixed).or_else(|| env_inner(name))
+        }
+
+        env("OPENSSL_INCLUDE_DIR").and_then(|path| {
             Path::new(&path)
                 .parent()
                 .map(|path| path.display().to_string())
@@ -305,37 +324,6 @@ mod build {
 
         bindings::place_bindings(&inc_dir);
 
-        // Link in the SSL libraries if configured for it.
-        if cfg!(feature = "ssl") {
-            if let Some(openssl_root_dir) = openssl_root_dir() {
-                println!("cargo:rustc-link-search={}/lib", openssl_root_dir);
-            }
-
-            // See if static SSL linkage was requested
-            let linkage = match env::var("OPENSSL_STATIC")
-                .as_ref()
-                .map(|s| s.as_str())
-            {
-                Ok("0") => "",
-                Ok(_) => "=static",
-                Err(_) => ""
-            };
-
-            let prefix = if is_msvc() { "lib" } else { "" };
-
-            println!("cargo:rustc-link-lib{}={}ssl", linkage, prefix);
-            println!("cargo:rustc-link-lib{}={}crypto", linkage, prefix);
-
-            if is_windows() {
-                if !is_msvc() {
-                    // required for mingw builds
-                    println!("cargo:rustc-link-lib{}=crypt32", linkage);
-                    println!("cargo:rustc-link-lib{}=rpcrt4", linkage);
-                }
-                println!("cargo:rustc-link-lib=User32");
-            }
-        }
-
         // we add the folder where all the libraries are built to the path search
         println!("cargo:rustc-link-search=native={}", lib_path.display());
         println!("cargo:rustc-link-lib=static={}", link_lib);
diff --git a/paho-mqtt-sys/paho.mqtt.c b/paho-mqtt-sys/paho.mqtt.c
index 07a8757..f7799da 160000
--- a/paho-mqtt-sys/paho.mqtt.c
+++ b/paho-mqtt-sys/paho.mqtt.c
@@ -1 +1 @@
-Subproject commit 07a875788d8cc6f5833b12581d6e3e349b34d719
+Subproject commit f7799da95e347bbc930b201b52a1173ebbad45a7
diff --git a/paho-mqtt-sys/src/lib.rs b/paho-mqtt-sys/src/lib.rs
index 879d665..61cebbf 100644
--- a/paho-mqtt-sys/src/lib.rs
+++ b/paho-mqtt-sys/src/lib.rs
@@ -23,16 +23,20 @@
 #![allow(non_upper_case_globals)]
 #![allow(non_camel_case_types)]
 #![allow(non_snake_case)]
-
 // Weirdness in the bindgen bindings
 #![allow(deref_nullptr)]
-
 // Temporary
 #![allow(dead_code)]
 
-use std::ptr;
 use std::fmt;
 use std::os::raw::{c_char, c_int};
+use std::ptr;
+
+#[cfg(feature = "ssl")]
+mod __make_openssl_linkage_work {
+    #[allow(unused_imports)]
+    use openssl_sys::*;
+}
 
 include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
 
@@ -52,7 +56,12 @@ impl Default for MQTTAsync_createOptions {
     /// Creates a client that can connect using MQTT v3.x or v5
     fn default() -> Self {
         Self {
-            struct_id: [ b'M' as c_char, b'Q' as c_char, b'C' as c_char, b'O' as c_char],
+            struct_id: [
+                b'M' as c_char,
+                b'Q' as c_char,
+                b'C' as c_char,
+                b'O' as c_char,
+            ],
             struct_version: CREATE_OPTIONS_STRUCT_VERSION,
             sendWhileDisconnected: 0,
             maxBufferedMessages: 100,
@@ -98,7 +107,12 @@ pub const CONNECT_OPTIONS_STRUCT_VERSION: i32 = 8;
 impl Default for MQTTAsync_connectOptions {
     fn default() -> Self {
         Self {
-            struct_id: [ b'M' as c_char, b'Q' as c_char, b'T' as c_char, b'C' as c_char],
+            struct_id: [
+                b'M' as c_char,
+                b'Q' as c_char,
+                b'T' as c_char,
+                b'C' as c_char,
+            ],
             struct_version: CONNECT_OPTIONS_STRUCT_VERSION,
             keepAliveInterval: 60,
             cleansession: 1,
@@ -181,7 +195,12 @@ pub const WILL_OPTIONS_STRUCT_VERSION: i32 = 1;
 impl Default for MQTTAsync_willOptions {
     fn default() -> MQTTAsync_willOptions {
         MQTTAsync_willOptions {
-            struct_id: [ b'M' as c_char, b'Q' as c_char, b'T' as c_char, b'W' as c_char ],
+            struct_id: [
+                b'M' as c_char,
+                b'Q' as c_char,
+                b'T' as c_char,
+                b'W' as c_char,
+            ],
             struct_version: WILL_OPTIONS_STRUCT_VERSION,
             topicName: ptr::null(),
             message: ptr::null(),
@@ -190,7 +209,7 @@ impl Default for MQTTAsync_willOptions {
             payload: MQTTAsync_willOptions__bindgen_ty_1 {
                 len: 0,
                 data: ptr::null(),
-            }
+            },
         }
     }
 }
@@ -201,7 +220,12 @@ pub const SSL_OPTIONS_STRUCT_VERSION: i32 = 5;
 impl Default for MQTTAsync_SSLOptions {
     fn default() -> MQTTAsync_SSLOptions {
         MQTTAsync_SSLOptions {
-            struct_id: [ b'M' as c_char, b'Q' as c_char, b'T' as c_char, b'S' as c_char ],
+            struct_id: [
+                b'M' as c_char,
+                b'Q' as c_char,
+                b'T' as c_char,
+                b'S' as c_char,
+            ],
             struct_version: SSL_OPTIONS_STRUCT_VERSION,
             trustStore: ptr::null(),
             keyStore: ptr::null(),
@@ -230,7 +254,12 @@ pub const SUBSCRIBE_OPTIONS_STRUCT_VERSION: i32 = 0;
 impl Default for MQTTSubscribe_options {
     fn default() -> MQTTSubscribe_options {
         MQTTSubscribe_options {
-            struct_id: [ b'M' as c_char, b'Q' as c_char, b'S' as c_char, b'O' as c_char ],
+            struct_id: [
+                b'M' as c_char,
+                b'Q' as c_char,
+                b'S' as c_char,
+                b'O' as c_char,
+            ],
             struct_version: SUBSCRIBE_OPTIONS_STRUCT_VERSION,
             noLocal: 0,
             retainAsPublished: 0,
@@ -245,7 +274,12 @@ pub const RESPONSE_OPTIONS_STRUCT_VERSION: i32 = 1;
 impl Default for MQTTAsync_responseOptions {
     fn default() -> MQTTAsync_responseOptions {
         MQTTAsync_responseOptions {
-            struct_id: [ b'M' as c_char, b'Q' as c_char, b'T' as c_char, b'R' as c_char ],
+            struct_id: [
+                b'M' as c_char,
+                b'Q' as c_char,
+                b'T' as c_char,
+                b'R' as c_char,
+            ],
             struct_version: RESPONSE_OPTIONS_STRUCT_VERSION,
             onSuccess: None,
             onFailure: None,
@@ -284,7 +318,10 @@ impl Default for MQTTProperties {
 
 impl Default for MQTTLenString {
     fn default() -> MQTTLenString {
-        MQTTLenString { len: 0, data: ptr::null_mut(), }
+        MQTTLenString {
+            len: 0,
+            data: ptr::null_mut(),
+        }
     }
 }
 
@@ -297,7 +334,12 @@ pub const MESSAGE_STRUCT_VERSION: i32 = 1;
 impl Default for MQTTAsync_message {
     fn default() -> MQTTAsync_message {
         MQTTAsync_message {
-            struct_id: [ b'M' as c_char, b'Q' as c_char, b'T' as c_char, b'M' as c_char ],
+            struct_id: [
+                b'M' as c_char,
+                b'Q' as c_char,
+                b'T' as c_char,
+                b'M' as c_char,
+            ],
             struct_version: MESSAGE_STRUCT_VERSION,
             payloadlen: 0,
             payload: ptr::null_mut(),
@@ -319,7 +361,12 @@ pub const DISCONNECT_OPTIONS_STRUCT_VERSION: i32 = 1;
 impl Default for MQTTAsync_disconnectOptions {
     fn default() -> MQTTAsync_disconnectOptions {
         MQTTAsync_disconnectOptions {
-            struct_id: [ b'M' as c_char, b'Q' as c_char, b'T' as c_char, b'D' as c_char],
+            struct_id: [
+                b'M' as c_char,
+                b'Q' as c_char,
+                b'T' as c_char,
+                b'D' as c_char,
+            ],
             struct_version: DISCONNECT_OPTIONS_STRUCT_VERSION,
             timeout: 0,
             onSuccess: None,
@@ -363,7 +410,10 @@ impl MQTTAsync_nameValue {
 
 impl Default for MQTTAsync_nameValue {
     fn default() -> Self {
-        Self { name: ptr::null(), value: ptr::null() }
+        Self {
+            name: ptr::null(),
+            value: ptr::null(),
+        }
     }
 }
 
@@ -371,6 +421,4 @@ impl Default for MQTTAsync_nameValue {
 // Unit Tests
 
 #[cfg(test)]
-mod tests {
-}
-
+mod tests {}