diff --git a/builtin/commit.c b/builtin/commit.c
index b02e2c4e89..d8d6dd5eaa 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -103,7 +103,7 @@ static enum commit_whence whence;
 static int use_editor = 1, include_status = 1;
 static int show_ignored_in_status;
 static const char *only_include_assumed;
-static struct strbuf message;
+static struct strbuf message = STRBUF_INIT;
 
 static int null_termination;
 static enum {
diff --git a/builtin/merge.c b/builtin/merge.c
index 1387376248..7d92e2064b 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -48,7 +48,7 @@ static int show_diffstat = 1, shortlog_len, squash;
 static int option_commit = 1, allow_fast_forward = 1;
 static int fast_forward_only, option_edit;
 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 struct strategy **use_strategies;
 static size_t use_strategies_nr, use_strategies_alloc;