diff --git a/contrib/guix/libexec/make_release_tarball.sh b/contrib/guix/libexec/make_release_tarball.sh
index af518b1542..f2e8449933 100755
--- a/contrib/guix/libexec/make_release_tarball.sh
+++ b/contrib/guix/libexec/make_release_tarball.sh
@@ -15,6 +15,11 @@ 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 ecc96160e6..963113ae2c 100755
--- a/share/genbuild.sh
+++ b/share/genbuild.sh
@@ -18,9 +18,14 @@ else
     exit 1
 fi
 
+# This checks that we are actually part of the intended git repository, and not just getting info about some unrelated git repository that the code happens to be in a directory under
+git_check_in_repo() {
+    ! { git status --porcelain -uall --ignored "$@" 2>/dev/null || echo '??'; } | grep -q '?'
+}
+
 GIT_TAG=""
 GIT_COMMIT=""
-if [ "${BITCOIN_GENBUILD_NO_GIT}" != "1" ] && [ -e "$(command -v git)" ] && [ "$(git rev-parse --is-inside-work-tree 2>/dev/null)" = "true" ]; then
+if [ "${BITCOIN_GENBUILD_NO_GIT}" != "1" ] && [ -e "$(command -v git)" ] && [ "$(git rev-parse --is-inside-work-tree 2>/dev/null)" = "true" ] && git_check_in_repo share/genbuild.sh; then
     # clean 'dirty' status of touched files that haven't been modified
     git diff >/dev/null 2>/dev/null
 
@@ -40,7 +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