2 files changed, 4 insertions, 1 deletions

diff --git a/.SRCINFO b/.SRCINFO
index 2466aae39b90..80358618f237 100644
--- a/.SRCINFO
+++ b/.SRCINFO
@@ -11,6 +11,7 @@ pkgbase = gtirb-git
 	makedepends = doxygen
 	makedepends = graphviz
 	optdepends = boost: build against system boost
+	optdepends = protobuf: multi-language access to serialized GTIRB
 	provides = gtirb
 	source = git://github.com/grammatech/gtirb.git
 	sha512sums = SKIP
diff --git a/PKGBUILD b/PKGBUILD
index bab8f43eebad..820239a08cdf 100644
--- a/PKGBUILD
+++ b/PKGBUILD
@@ -8,7 +8,9 @@ pkgdesc="GrammaTech Intermediate Representation for Binaries"
 arch=('x86_64')
 url="https://github.com/grammatech/gtirb"
 license=('MIT')
-optdepends=('boost: build against system boost')
+optdepends=('boost: build against system boost'
+            # Installed protobuf package also dramatically reduces build time.
+            'protobuf: multi-language access to serialized GTIRB')
 depends=()
 # graphviz -- to build the docs
 makedepends=('git' 'cmake' 'python' 'doxygen' 'graphviz')