diff --git a/projects/firefox/build.sh b/projects/firefox/build.sh
index 80e8b5c3d..ea0a50946 100755
--- a/projects/firefox/build.sh
+++ b/projects/firefox/build.sh
@@ -47,6 +47,8 @@ ac_add_options --enable-address-sanitizer
 EOF
 fi
 
+source /root/.cargo/env
+
 # Build! Takes about 15 minutes on a 32 vCPU instance.
 ./mach build
 ./mach gtest buildbutdontrun