diff --git a/cbindgen/.signature b/cbindgen/.signature
index 584a63353..9014e7e70 100644
--- a/cbindgen/.signature
+++ b/cbindgen/.signature
@@ -1,5 +1,6 @@
 untrusted comment: verify with /etc/ports/contrib.pub
-RWSagIOpLGJF3wf7xjlon4vGEZMelA+XgeMzjRovvUvEbwkPdNPFsnzmhc5gBF4EsVioGyOYvYm0Ac/NUd/JIJ85NkcrWdd2XwU=
-SHA256 (Pkgfile) = 46e235f1f717d14bc087e24952b0ad03b035eac217d29dced9be1ef15a802a2a
+RWSagIOpLGJF31KiF7uEkehoyT1DVyiSyrHLhO/HYCohGSDNq+goWiEYetJwTV16P/ndRqrrtQj6Q8pYxStwFsCYzNIq0NoiSwk=
+SHA256 (Pkgfile) = 190b594d6fcf4d6569f79cc59cc3cc143fe7301b886e8009da38230360f3ecbb
 SHA256 (.footprint) = fd60992957bd0010460d49684c69464200651af797acdb98547f4847fc9f3f3c
 SHA256 (cbindgen-v0.14.0.tar.gz) = d3d077de08f09386d3a4db6cc9e79cf0e819c01712eb2476c786c119dab0108c
+SHA256 (firefox.patch) = d260660e51a751c9dd6a3bc721c31898f01fe6a373963d37e272f35ffc34b6e8
diff --git a/cbindgen/Pkgfile b/cbindgen/Pkgfile
index c00510555..347b7b23d 100644
--- a/cbindgen/Pkgfile
+++ b/cbindgen/Pkgfile
@@ -6,12 +6,16 @@
 
 name=cbindgen
 version=0.14.0
-release=1
-source=(https://github.com/eqrion/cbindgen/archive/v$version/$name-v$version.tar.gz)
+release=2
+source=(https://github.com/eqrion/cbindgen/archive/v$version/$name-v$version.tar.gz
+	firefox.patch)
 
 build() {
 	cd $name-$version
 
+	# https://github.com/eqrion/cbindgen/issues/500
+	patch -p1 -R -i $SRC/firefox.patch
+
 	prt-get isinst sccache && export RUSTC_WRAPPER=/usr/bin/sccache
 	mkdir "$PKGMK_SOURCE_DIR/rust" || true
 	export CARGO_HOME="$PKGMK_SOURCE_DIR/rust"
diff --git a/cbindgen/firefox.patch b/cbindgen/firefox.patch
new file mode 100644
index 000000000..ffb06cc76
--- /dev/null
+++ b/cbindgen/firefox.patch
@@ -0,0 +1,255 @@
+From ec1631f3e47686e6e0c1b7641bb08b0e39c59250 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
+Date: Tue, 31 Mar 2020 17:41:48 +0200
+Subject: [PATCH] Allow excluding monomorph structs in C mode.
+
+Fixes #500.
+---
+ src/bindgen/library.rs                        |  4 +++-
+ .../both/exclude_generic_monomorph.c          | 15 ++++++++++++
+ .../both/exclude_generic_monomorph.compat.c   | 23 +++++++++++++++++++
+ .../expectations/exclude_generic_monomorph.c  | 15 ++++++++++++
+ .../exclude_generic_monomorph.compat.c        | 23 +++++++++++++++++++
+ .../exclude_generic_monomorph.cpp             | 15 ++++++++++++
+ .../tag/exclude_generic_monomorph.c           | 15 ++++++++++++
+ .../tag/exclude_generic_monomorph.compat.c    | 23 +++++++++++++++++++
+ tests/rust/exclude_generic_monomorph.rs       | 10 ++++++++
+ tests/rust/exclude_generic_monomorph.toml     | 11 +++++++++
+ 10 files changed, 153 insertions(+), 1 deletion(-)
+ create mode 100644 tests/expectations/both/exclude_generic_monomorph.c
+ create mode 100644 tests/expectations/both/exclude_generic_monomorph.compat.c
+ create mode 100644 tests/expectations/exclude_generic_monomorph.c
+ create mode 100644 tests/expectations/exclude_generic_monomorph.compat.c
+ create mode 100644 tests/expectations/exclude_generic_monomorph.cpp
+ create mode 100644 tests/expectations/tag/exclude_generic_monomorph.c
+ create mode 100644 tests/expectations/tag/exclude_generic_monomorph.compat.c
+ create mode 100644 tests/rust/exclude_generic_monomorph.rs
+ create mode 100644 tests/rust/exclude_generic_monomorph.toml
+
+diff --git a/src/bindgen/library.rs b/src/bindgen/library.rs
+index 0cdd07ea..4cb0b8b8 100644
+--- a/src/bindgen/library.rs
++++ b/src/bindgen/library.rs
+@@ -54,7 +54,6 @@ impl Library {
+     }
+ 
+     pub fn generate(mut self) -> Result<Bindings, Error> {
+-        self.remove_excluded();
+         self.transfer_annotations();
+         self.simplify_standard_types();
+ 
+@@ -67,7 +66,10 @@ impl Library {
+ 
+         if self.config.language == Language::C {
+             self.instantiate_monomorphs();
++            self.remove_excluded();
+             self.resolve_declaration_types();
++        } else {
++            self.remove_excluded();
+         }
+ 
+         self.rename_items();
+diff --git a/tests/expectations/both/exclude_generic_monomorph.c b/tests/expectations/both/exclude_generic_monomorph.c
+new file mode 100644
+index 00000000..2d43ce15
+--- /dev/null
++++ b/tests/expectations/both/exclude_generic_monomorph.c
+@@ -0,0 +1,15 @@
++#include <stdint.h>
++
++typedef uint64_t Option_Foo;
++
++
++#include <stdarg.h>
++#include <stdbool.h>
++#include <stdint.h>
++#include <stdlib.h>
++
++typedef struct Bar {
++  Option_Foo foo;
++} Bar;
++
++void root(Bar f);
+diff --git a/tests/expectations/both/exclude_generic_monomorph.compat.c b/tests/expectations/both/exclude_generic_monomorph.compat.c
+new file mode 100644
+index 00000000..76a0a3bb
+--- /dev/null
++++ b/tests/expectations/both/exclude_generic_monomorph.compat.c
+@@ -0,0 +1,23 @@
++#include <stdint.h>
++
++typedef uint64_t Option_Foo;
++
++
++#include <stdarg.h>
++#include <stdbool.h>
++#include <stdint.h>
++#include <stdlib.h>
++
++typedef struct Bar {
++  Option_Foo foo;
++} Bar;
++
++#ifdef __cplusplus
++extern "C" {
++#endif // __cplusplus
++
++void root(Bar f);
++
++#ifdef __cplusplus
++} // extern "C"
++#endif // __cplusplus
+diff --git a/tests/expectations/exclude_generic_monomorph.c b/tests/expectations/exclude_generic_monomorph.c
+new file mode 100644
+index 00000000..e7178367
+--- /dev/null
++++ b/tests/expectations/exclude_generic_monomorph.c
+@@ -0,0 +1,15 @@
++#include <stdint.h>
++
++typedef uint64_t Option_Foo;
++
++
++#include <stdarg.h>
++#include <stdbool.h>
++#include <stdint.h>
++#include <stdlib.h>
++
++typedef struct {
++  Option_Foo foo;
++} Bar;
++
++void root(Bar f);
+diff --git a/tests/expectations/exclude_generic_monomorph.compat.c b/tests/expectations/exclude_generic_monomorph.compat.c
+new file mode 100644
+index 00000000..062e71ca
+--- /dev/null
++++ b/tests/expectations/exclude_generic_monomorph.compat.c
+@@ -0,0 +1,23 @@
++#include <stdint.h>
++
++typedef uint64_t Option_Foo;
++
++
++#include <stdarg.h>
++#include <stdbool.h>
++#include <stdint.h>
++#include <stdlib.h>
++
++typedef struct {
++  Option_Foo foo;
++} Bar;
++
++#ifdef __cplusplus
++extern "C" {
++#endif // __cplusplus
++
++void root(Bar f);
++
++#ifdef __cplusplus
++} // extern "C"
++#endif // __cplusplus
+diff --git a/tests/expectations/exclude_generic_monomorph.cpp b/tests/expectations/exclude_generic_monomorph.cpp
+new file mode 100644
+index 00000000..e7178367
+--- /dev/null
++++ b/tests/expectations/exclude_generic_monomorph.cpp
+@@ -0,0 +1,15 @@
++#include <stdint.h>
++
++typedef uint64_t Option_Foo;
++
++
++#include <stdarg.h>
++#include <stdbool.h>
++#include <stdint.h>
++#include <stdlib.h>
++
++typedef struct {
++  Option_Foo foo;
++} Bar;
++
++void root(Bar f);
+diff --git a/tests/expectations/tag/exclude_generic_monomorph.c b/tests/expectations/tag/exclude_generic_monomorph.c
+new file mode 100644
+index 00000000..32686ad9
+--- /dev/null
++++ b/tests/expectations/tag/exclude_generic_monomorph.c
+@@ -0,0 +1,15 @@
++#include <stdint.h>
++
++typedef uint64_t Option_Foo;
++
++
++#include <stdarg.h>
++#include <stdbool.h>
++#include <stdint.h>
++#include <stdlib.h>
++
++struct Bar {
++  Option_Foo foo;
++};
++
++void root(struct Bar f);
+diff --git a/tests/expectations/tag/exclude_generic_monomorph.compat.c b/tests/expectations/tag/exclude_generic_monomorph.compat.c
+new file mode 100644
+index 00000000..27408515
+--- /dev/null
++++ b/tests/expectations/tag/exclude_generic_monomorph.compat.c
+@@ -0,0 +1,23 @@
++#include <stdint.h>
++
++typedef uint64_t Option_Foo;
++
++
++#include <stdarg.h>
++#include <stdbool.h>
++#include <stdint.h>
++#include <stdlib.h>
++
++struct Bar {
++  Option_Foo foo;
++};
++
++#ifdef __cplusplus
++extern "C" {
++#endif // __cplusplus
++
++void root(struct Bar f);
++
++#ifdef __cplusplus
++} // extern "C"
++#endif // __cplusplus
+diff --git a/tests/rust/exclude_generic_monomorph.rs b/tests/rust/exclude_generic_monomorph.rs
+new file mode 100644
+index 00000000..78fd1973
+--- /dev/null
++++ b/tests/rust/exclude_generic_monomorph.rs
+@@ -0,0 +1,10 @@
++#[repr(transparent)]
++pub struct Foo(NonZeroU64);
++
++#[repr(C)]
++pub struct Bar {
++  foo: Option<Foo>,
++}
++
++#[no_mangle]
++pub extern "C" fn root(f: Bar) {}
+diff --git a/tests/rust/exclude_generic_monomorph.toml b/tests/rust/exclude_generic_monomorph.toml
+new file mode 100644
+index 00000000..82d33617
+--- /dev/null
++++ b/tests/rust/exclude_generic_monomorph.toml
+@@ -0,0 +1,11 @@
++language = "C"
++header = """
++#include <stdint.h>
++
++typedef uint64_t Option_Foo;
++"""
++
++[export]
++exclude = [
++  "Option_Foo",
++]