diff --git a/builtin-commit.c b/builtin-commit.c
index 7434797d1b..5b418a53f8 100644
--- a/builtin-commit.c
+++ b/builtin-commit.c
@@ -69,7 +69,7 @@ static char *cleanup_arg;
 
 static int use_editor = 1, initial_commit, in_merge;
 static const char *only_include_assumed;
-static struct strbuf message;
+static struct strbuf message = STRBUF_INIT;
 
 static int opt_parse_m(const struct option *opt, const char *arg, int unset)
 {
diff --git a/builtin-merge.c b/builtin-merge.c
index 8825dcf8d9..49e9115ec4 100644
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@ -42,7 +42,7 @@ static const char * const builtin_merge_usage[] = {
 static int show_diffstat = 1, option_log, squash;
 static int option_commit = 1, allow_fast_forward = 1;
 static int allow_trivial = 1, have_message;
-static struct strbuf merge_msg;
+static struct strbuf merge_msg = STRBUF_INIT;
 static struct commit_list *remoteheads;
 static unsigned char head[20], stash[20];
 static struct strategy **use_strategies;