diff --git a/libc-test/build.rs b/libc-test/build.rs
index dab69ecf..c68fae6e 100644
--- a/libc-test/build.rs
+++ b/libc-test/build.rs
@@ -350,10 +350,6 @@ fn main() {
             // they're implemented on rumprun yet, just let them slide for now.
             // Some of them look like they have headers but then don't have
             // corresponding actual definitions either...
-            "backtrace" |
-            "pthread_main_np" |
-            "pthread_set_name_np" |
-            "pthread_stackseg_np" |
             "shm_open" |
             "shm_unlink" |
             "syscall" |
diff --git a/src/lib.rs b/src/lib.rs
index c9d7701a..57919c59 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -74,7 +74,7 @@
 ))]
 
 // Attributes needed when building as part of the standard library
-#![cfg_attr(stdbuild, feature(no_std, core, core_slice_ext, staged_api, custom_attribute))]
+#![cfg_attr(stdbuild, feature(no_std, core, core_slice_ext, staged_api, custom_attribute, cfg_target_vendor))]
 #![cfg_attr(stdbuild, no_std)]
 #![cfg_attr(stdbuild, staged_api)]
 #![cfg_attr(stdbuild, allow(warnings))]
diff --git a/src/macros.rs b/src/macros.rs
index 3c2978ea..5811c84c 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -23,7 +23,7 @@ macro_rules! cfg_if {
 macro_rules! __cfg_if_items {
     (($($not:meta,)*) ; ) => {};
     (($($not:meta,)*) ; ( ($($m:meta),*) ($($it:item)*) ), $($rest:tt)*) => {
-        __cfg_if_apply! { cfg(all($($m,)* not(any($($not),*)))), $($it)* }
+        __cfg_if_apply! { cfg(all(not(any($($not),*)), $($m,)*)), $($it)* }
         __cfg_if_items! { ($($not,)* $($m,)*) ; $($rest)* }
     }
 }
diff --git a/src/unix/bsd/openbsdlike/bitrig.rs b/src/unix/bsd/openbsdlike/bitrig.rs
index ab9cc9f0..b6c51dec 100644
--- a/src/unix/bsd/openbsdlike/bitrig.rs
+++ b/src/unix/bsd/openbsdlike/bitrig.rs
@@ -227,6 +227,10 @@ extern {
                        flags: ::c_int) -> ::c_int;
     pub fn mprotect(addr: *const ::c_void, len: ::size_t, prot: ::c_int)
                     -> ::c_int;
+    pub fn pthread_main_np() -> ::c_int;
+    pub fn pthread_set_name_np(tid: ::pthread_t, name: *const ::c_char);
+    pub fn pthread_stackseg_np(thread: ::pthread_t,
+                               sinfo: *mut ::stack_t) -> ::c_int;
     pub fn sysctl(name: *mut ::c_int,
                   namelen: ::c_uint,
                   oldp: *mut ::c_void,
diff --git a/src/unix/bsd/openbsdlike/mod.rs b/src/unix/bsd/openbsdlike/mod.rs
index 490e8056..c8b17bb2 100644
--- a/src/unix/bsd/openbsdlike/mod.rs
+++ b/src/unix/bsd/openbsdlike/mod.rs
@@ -384,10 +384,6 @@ extern {
     pub fn __errno() -> *mut ::c_int;
     pub fn shm_open(name: *const ::c_char, oflag: ::c_int, mode: ::mode_t)
                     -> ::c_int;
-    pub fn pthread_main_np() -> ::c_int;
-    pub fn pthread_set_name_np(tid: ::pthread_t, name: *const ::c_char);
-    pub fn pthread_stackseg_np(thread: ::pthread_t,
-                               sinfo: *mut ::stack_t) -> ::c_int;
     pub fn memrchr(cx: *const ::c_void, c: ::c_int, n: ::size_t) -> *mut ::c_void;
     pub fn mkostemp(template: *mut ::c_char, flags: ::c_int) -> ::c_int;
     pub fn mkostemps(template: *mut ::c_char, suffixlen: ::c_int, flags: ::c_int) -> ::c_int;
diff --git a/src/unix/bsd/openbsdlike/openbsd.rs b/src/unix/bsd/openbsdlike/openbsd.rs
index fc38478f..73d14ea9 100644
--- a/src/unix/bsd/openbsdlike/openbsd.rs
+++ b/src/unix/bsd/openbsdlike/openbsd.rs
@@ -232,6 +232,10 @@ extern {
                        flags: ::c_int) -> ::c_int;
     pub fn mprotect(addr: *mut ::c_void, len: ::size_t, prot: ::c_int)
                     -> ::c_int;
+    pub fn pthread_main_np() -> ::c_int;
+    pub fn pthread_set_name_np(tid: ::pthread_t, name: *const ::c_char);
+    pub fn pthread_stackseg_np(thread: ::pthread_t,
+                               sinfo: *mut ::stack_t) -> ::c_int;
     pub fn sysctl(name: *const ::c_int,
                   namelen: ::c_uint,
                   oldp: *mut ::c_void,
diff --git a/src/unix/mod.rs b/src/unix/mod.rs
index f65efd63..2e9b44cb 100644
--- a/src/unix/mod.rs
+++ b/src/unix/mod.rs
@@ -143,6 +143,12 @@ cfg_if! {
     } else if #[cfg(target_os = "emscripten")] {
         #[link(name = "c")]
         extern {}
+    } else if #[cfg(all(target_vendor = "rumprun", target_os = "netbsd"))] {
+        // Since we don't use -nodefaultlibs on Rumprun, libc is always pulled in
+        // automatically by the linker. We avoid passing it explicitly, as it
+        // causes some versions of binutils to crash with an assertion failure.
+        #[link(name = "m")]
+        extern {}
     } else if #[cfg(any(target_os = "macos",
                         target_os = "ios",
                         target_os = "android",