diff --git a/spa/tests/test-json.c b/spa/tests/test-json.c
index 78c383871..dd510841f 100644
--- a/spa/tests/test-json.c
+++ b/spa/tests/test-json.c
@@ -71,7 +71,7 @@ static void expect_string(struct spa_json *it, const char *str)
 	char *s;
 	spa_assert((len = spa_json_next(it, &value)) > 0);
 	check_type(TYPE_STRING, value, len);
-	s = alloca(len);
+	s = alloca(len+1);
 	spa_json_parse_string(value, len, s);
 	spa_assert(strcmp(s, str) == 0);
 }
diff --git a/src/daemon/main.c b/src/daemon/main.c
index 2b685d872..ef2a5fd17 100644
--- a/src/daemon/main.c
+++ b/src/daemon/main.c
@@ -168,7 +168,7 @@ static int parse_modules(struct data *d, const char *str)
 					if (spa_json_is_container(aval, alen))
 						alen = spa_json_container_len(&it[2], aval, alen);
 
-					args = malloc(alen);
+					args = malloc(alen + 1);
 					spa_json_parse_string(aval, alen, args);
 				} else if (strcmp(arg, "flags") == 0) {
 					flags = strndup(aval, alen);
@@ -249,7 +249,8 @@ static int parse_objects(struct data *d, const char *str)
 				if (strcmp(arg, "args") == 0) {
 					if (spa_json_is_container(aval, alen))
 						alen = spa_json_container_len(&it[2], aval, alen);
-					args = malloc(alen);
+
+					args = malloc(alen + 1);
 					spa_json_parse_string(aval, alen, args);
 				} else if (strcmp(arg, "flags") == 0) {
 					flags = strndup(aval, alen);
diff --git a/src/examples/media-session/match-rules.c b/src/examples/media-session/match-rules.c
index c6a382ede..234542fe5 100644
--- a/src/examples/media-session/match-rules.c
+++ b/src/examples/media-session/match-rules.c
@@ -60,7 +60,7 @@ static bool find_match(struct spa_json *arr, struct pw_properties *props)
 			if (spa_json_is_null(value, len)) {
 				success = str == NULL;
 			} else {
-				spa_json_parse_string(value, SPA_MIN(len, 1024), val);
+				spa_json_parse_string(value, SPA_MIN(len, 1023), val);
 				value = val;
 				len = strlen(val);
 			}
diff --git a/src/tools/pw-cli.c b/src/tools/pw-cli.c
index cf8093c8b..b682bf34e 100644
--- a/src/tools/pw-cli.c
+++ b/src/tools/pw-cli.c
@@ -1616,7 +1616,7 @@ static int json_to_pod(struct spa_pod_builder *b, uint32_t id,
 		spa_pod_builder_none(b);
 	}
 	else {
-		char *val = alloca(len);
+		char *val = alloca(len+1);
 		spa_json_parse_string(value, len, val);
 		switch (info->parent) {
 		case SPA_TYPE_Id: