diff --git a/binding.gyp b/binding.gyp
index 10e142f..b5a0ccb 100644
--- a/binding.gyp
+++ b/binding.gyp
@@ -51,7 +51,7 @@
                     "GCC_SYMBOLS_PRIVATE_EXTERN": "YES"
                 }
             }],
-            ["OS=='mac' or OS=='linux'", {
+            ["OS=='mac' or OS=='linux' or OS=='freebsd'", {
                 "defines": [
                     "OPA_HAVE_GCC_INTRINSIC_ATOMICS=1",
                     "HAVE_STDDEF_H=1",
diff --git a/vendor/openpa/openpa.gyp b/vendor/openpa/openpa.gyp
index 0ceeb4b..dde9c5d 100644
--- a/vendor/openpa/openpa.gyp
+++ b/vendor/openpa/openpa.gyp
@@ -45,7 +45,7 @@
                         }],
                     ]
                 }],
-                ["OS=='mac' or OS=='linux'", {
+                ["OS=='mac' or OS=='linux' or OS=='freebsd'", {
                     "sources": [
                         "src/primitives/opa_gcc_intrinsics.h"
                     ],