diff --git a/scripts/dtc/data.c b/scripts/dtc/data.c
index dd2e3d39d4c..fe555e819bf 100644
--- a/scripts/dtc/data.c
+++ b/scripts/dtc/data.c
@@ -217,7 +217,7 @@ struct data data_insert_at_marker(struct data d, struct marker *m,
 	return d;
 }
 
-struct data data_append_markers(struct data d, struct marker *m)
+static struct data data_append_markers(struct data d, struct marker *m)
 {
 	struct marker **mp = &d.markers;
 
diff --git a/scripts/dtc/libfdt/fdt_ro.c b/scripts/dtc/libfdt/fdt_ro.c
index fbbba44fcd0..22e692919ff 100644
--- a/scripts/dtc/libfdt/fdt_ro.c
+++ b/scripts/dtc/libfdt/fdt_ro.c
@@ -411,7 +411,7 @@ int fdt_node_offset_by_phandle(const void *fdt, uint32_t phandle)
 					     &phandle, sizeof(phandle));
 }
 
-int _stringlist_contains(const char *strlist, int listlen, const char *str)
+static int _stringlist_contains(const char *strlist, int listlen, const char *str)
 {
 	int len = strlen(str);
 	const char *p;
diff --git a/scripts/dtc/treesource.c b/scripts/dtc/treesource.c
index ebeb6eb2790..1521ff11bb9 100644
--- a/scripts/dtc/treesource.c
+++ b/scripts/dtc/treesource.c
@@ -52,7 +52,7 @@ static void write_prefix(FILE *f, int level)
 		fputc('\t', f);
 }
 
-int isstring(char c)
+static int isstring(char c)
 {
 	return (isprint(c)
 		|| (c == '\0')