diff --git a/contrib/guix/libexec/make_release_tarball.sh b/contrib/guix/libexec/make_release_tarball.sh
index f930b78e09..c99e6fb500 100755
--- a/contrib/guix/libexec/make_release_tarball.sh
+++ b/contrib/guix/libexec/make_release_tarball.sh
@@ -14,6 +14,11 @@ GIT_ARCHIVE="$1"
 DISTNAME="$2"
 
 git archive --prefix="${DISTNAME}/" HEAD | tar -xp
+
+# Generate correct build info file from git, before we lose git
+GIT_BUILD_INFO="$(share/genbuild.sh /dev/stdout)"
+sed 's/\/\/ No build information available/'"${GIT_BUILD_INFO}"'/' -i "${DISTNAME}/share/genbuild.sh"
+
 cd "${DISTNAME}"
 
 ./autogen.sh
diff --git a/share/genbuild.sh b/share/genbuild.sh
index 26c1baa4a8..963113ae2c 100755
--- a/share/genbuild.sh
+++ b/share/genbuild.sh
@@ -45,7 +45,9 @@ if [ -n "$GIT_TAG" ]; then
 elif [ -n "$GIT_COMMIT" ]; then
     NEWINFO="#define BUILD_GIT_COMMIT \"$GIT_COMMIT\""
 else
-    NEWINFO="// No build information available"
+    # NOTE: The NEWINFO line below this comment gets replaced by a string-match in contrib/guix/libexec/make_release_tarball.sh
+    # If changing it, update the script too!
+    NEWINFO='// No build information available'
 fi
 
 # only update build.h if necessary