diff --git a/tools/fdtgrep.c b/tools/fdtgrep.c
index 037176bc9ef..b4c041070f5 100644
--- a/tools/fdtgrep.c
+++ b/tools/fdtgrep.c
@@ -1040,7 +1040,7 @@ static const char * const usage_opts_help[] = {
 #define util_getopt_long() getopt_long(argc, argv, usage_short_opts, \
 				       usage_long_opts, NULL)
 
-void util_usage(const char *errmsg, const char *synopsis,
+static void util_usage(const char *errmsg, const char *synopsis,
 		const char *short_opts, struct option const long_opts[],
 		const char * const opts_help[])
 {
@@ -1109,7 +1109,7 @@ void util_usage(const char *errmsg, const char *synopsis,
 	util_usage(errmsg, usage_synopsis, usage_short_opts, \
 		   usage_long_opts, usage_opts_help)
 
-void util_version(void)
+static void util_version(void)
 {
 	printf("Version: %s\n", "(U-Boot)");
 	exit(0);
diff --git a/tools/fit_check_sign.c b/tools/fit_check_sign.c
index 32d0fdb8829..ab3266aff20 100644
--- a/tools/fit_check_sign.c
+++ b/tools/fit_check_sign.c
@@ -23,7 +23,7 @@
 #include <image.h>
 #include <u-boot/crc.h>
 
-void usage(char *cmdname)
+static void usage(char *cmdname)
 {
 	fprintf(stderr, "Usage: %s -f fit file -k key file -c config name\n"
 			 "          -f ==> set fit file which should be checked'\n"
diff --git a/tools/imx8mimage.c b/tools/imx8mimage.c
index 0f24ba75c0f..3e974923652 100644
--- a/tools/imx8mimage.c
+++ b/tools/imx8mimage.c
@@ -49,7 +49,7 @@ static uint32_t get_cfg_value(char *token, char *name,  int linenr)
 	return value;
 }
 
-int imx8mimage_check_params(struct image_tool_params *params)
+static int imx8mimage_check_params(struct image_tool_params *params)
 {
 	return 0;
 }
@@ -475,7 +475,7 @@ static int generate_fspi_header (int ifd)
 }
 #endif
 
-void build_image(int ofd)
+static void build_image(int ofd)
 {
 	int file_off, header_hdmi_off = 0, header_image_off;
 
diff --git a/tools/mkimage.c b/tools/mkimage.c
index 361711c53b2..847453970ab 100644
--- a/tools/mkimage.c
+++ b/tools/mkimage.c
@@ -445,7 +445,7 @@ static void verify_image(const struct image_type_params *tparams)
 	(void)close(ifd);
 }
 
-void copy_datafile(int ifd, char *file)
+static void copy_datafile(int ifd, char *file)
 {
 	if (!file)
 		return;
diff --git a/tools/rkcommon.c b/tools/rkcommon.c
index a0caa029cc0..d191ea72c63 100644
--- a/tools/rkcommon.c
+++ b/tools/rkcommon.c
@@ -279,7 +279,7 @@ bool rkcommon_need_rc4_spl(struct image_tool_params *params)
 	return info->spl_rc4;
 }
 
-bool rkcommon_is_header_v2(struct image_tool_params *params)
+static bool rkcommon_is_header_v2(struct image_tool_params *params)
 {
 	struct spl_info *info = rkcommon_get_spl_info(params->imagename);