diff --git a/src/liballoc_jemalloc/lib.rs b/src/liballoc_jemalloc/lib.rs
index 80a831fd20775..f46b12e80c56a 100644
--- a/src/liballoc_jemalloc/lib.rs
+++ b/src/liballoc_jemalloc/lib.rs
@@ -43,8 +43,7 @@ use libc::{c_int, c_void, size_t};
 extern {
     fn je_mallocx(size: size_t, flags: c_int) -> *mut c_void;
     fn je_rallocx(ptr: *mut c_void, size: size_t, flags: c_int) -> *mut c_void;
-    fn je_xallocx(ptr: *mut c_void, size: size_t, extra: size_t,
-                  flags: c_int) -> size_t;
+    fn je_xallocx(ptr: *mut c_void, size: size_t, extra: size_t, flags: c_int) -> size_t;
     fn je_sdallocx(ptr: *mut c_void, size: size_t, flags: c_int);
     fn je_nallocx(size: size_t, flags: c_int) -> size_t;
 }
@@ -63,40 +62,52 @@ const MIN_ALIGN: usize = 8;
 const MIN_ALIGN: usize = 16;
 
 // MALLOCX_ALIGN(a) macro
-fn mallocx_align(a: usize) -> c_int { a.trailing_zeros() as c_int }
+fn mallocx_align(a: usize) -> c_int {
+    a.trailing_zeros() as c_int
+}
 
 fn align_to_flags(align: usize) -> c_int {
-    if align <= MIN_ALIGN { 0 } else { mallocx_align(align) }
+    if align <= MIN_ALIGN {
+        0
+    } else {
+        mallocx_align(align)
+    }
 }
 
 #[no_mangle]
-pub extern fn __rust_allocate(size: usize, align: usize) -> *mut u8 {
+pub extern "C" fn __rust_allocate(size: usize, align: usize) -> *mut u8 {
     let flags = align_to_flags(align);
     unsafe { je_mallocx(size as size_t, flags) as *mut u8 }
 }
 
 #[no_mangle]
-pub extern fn __rust_reallocate(ptr: *mut u8, _old_size: usize, size: usize,
-                                align: usize) -> *mut u8 {
+pub extern "C" fn __rust_reallocate(ptr: *mut u8,
+                                    _old_size: usize,
+                                    size: usize,
+                                    align: usize)
+                                    -> *mut u8 {
     let flags = align_to_flags(align);
     unsafe { je_rallocx(ptr as *mut c_void, size as size_t, flags) as *mut u8 }
 }
 
 #[no_mangle]
-pub extern fn __rust_reallocate_inplace(ptr: *mut u8, _old_size: usize,
-                                        size: usize, align: usize) -> usize {
+pub extern "C" fn __rust_reallocate_inplace(ptr: *mut u8,
+                                            _old_size: usize,
+                                            size: usize,
+                                            align: usize)
+                                            -> usize {
     let flags = align_to_flags(align);
     unsafe { je_xallocx(ptr as *mut c_void, size as size_t, 0, flags) as usize }
 }
 
 #[no_mangle]
-pub extern fn __rust_deallocate(ptr: *mut u8, old_size: usize, align: usize) {
+pub extern "C" fn __rust_deallocate(ptr: *mut u8, old_size: usize, align: usize) {
     let flags = align_to_flags(align);
     unsafe { je_sdallocx(ptr as *mut c_void, old_size as size_t, flags) }
 }
 
 #[no_mangle]
-pub extern fn __rust_usable_size(size: usize, align: usize) -> usize {
+pub extern "C" fn __rust_usable_size(size: usize, align: usize) -> usize {
     let flags = align_to_flags(align);
     unsafe { je_nallocx(size as size_t, flags) as usize }
 }