diff --git a/include/zbxcommon.h b/include/zbxcommon.h
index b2efb120138..245d8b0c8fc 100644
--- a/include/zbxcommon.h
+++ b/include/zbxcommon.h
@@ -600,7 +600,7 @@ int	zbx_hpux_vsnprintf_is_c99(void);
 /* used by log */
 size_t	zbx_vsnprintf(char *str, size_t count, const char *fmt, va_list args);
 
-int	zbx_vsnprintf_check_len(const char *fmt, va_list args);
+size_t	zbx_vsnprintf_check_len(const char *fmt, va_list args);
 
 /* used by log */
 char	*zbx_dsprintf(char *dest, const char *f, ...) __zbx_attr_format_printf(2, 3);
diff --git a/src/go/pkg/zbxlib/log.go b/src/go/pkg/zbxlib/log.go
index d6c26d98d0e..dc4fe423ddd 100644
--- a/src/go/pkg/zbxlib/log.go
+++ b/src/go/pkg/zbxlib/log.go
@@ -38,8 +38,7 @@ void zbx_log_go_impl(int level, const char *fmt, va_list args)
 
 		va_copy(tmp, args);
 
-		// zbx_vsnprintf_check_len() cannot return negative result
-		size = (size_t)zbx_vsnprintf_check_len(fmt, tmp) + 2;
+		size = zbx_vsnprintf_check_len(fmt, tmp) + 2;
 
 		va_end(tmp);
 
diff --git a/src/libs/zbxcommon/common_str.c b/src/libs/zbxcommon/common_str.c
index 71cb90c4495..298c56b2ac1 100644
--- a/src/libs/zbxcommon/common_str.c
+++ b/src/libs/zbxcommon/common_str.c
@@ -51,7 +51,7 @@ size_t	zbx_vsnprintf(char *str, size_t count, const char *fmt, va_list args)
 	return (size_t)written_len;
 }
 
-int	zbx_vsnprintf_check_len(const char *fmt, va_list args)
+size_t	zbx_vsnprintf_check_len(const char *fmt, va_list args)
 {
 	int	rv;
 
@@ -61,7 +61,7 @@ int	zbx_vsnprintf_check_len(const char *fmt, va_list args)
 		exit(EXIT_FAILURE);
 	}
 
-	return rv;
+	return (size_t)rv;
 }
 
 /******************************************************************************
@@ -296,9 +296,8 @@ retry:
 	{
 		va_start(args, fmt);
 
-		/* zbx_vsnprintf_check_len() cannot return negative result. */
 		/* '\0' + one byte to prevent operation retry. */
-		*alloc_len = (size_t)zbx_vsnprintf_check_len(fmt, args) + 2;
+		*alloc_len = zbx_vsnprintf_check_len(fmt, args) + 2;
 
 		va_end(args);
 		*offset = 0;
diff --git a/src/libs/zbxlog/log.c b/src/libs/zbxlog/log.c
index 2651e499f09..3c1e54c961f 100644
--- a/src/libs/zbxlog/log.c
+++ b/src/libs/zbxlog/log.c
@@ -703,8 +703,7 @@ void	zbx_strlog_alloc(int level, char **out, size_t *out_alloc, size_t *out_offs
 #endif
 	va_start(args, format);
 
-	/* zbx_vsnprintf_check_len() cannot return negative result */
-	len = (size_t)zbx_vsnprintf_check_len(format, args) + 2;
+	len = zbx_vsnprintf_check_len(format, args) + 2;
 
 	va_end(args);
 
diff --git a/src/zabbix_server/ha/ha_manager.c b/src/zabbix_server/ha/ha_manager.c
index 69fe5506055..0f80fdb049e 100644
--- a/src/zabbix_server/ha/ha_manager.c
+++ b/src/zabbix_server/ha/ha_manager.c
@@ -254,8 +254,7 @@ static void	ha_set_error(zbx_ha_info_t *info, const char *fmt, ...)
 
 	va_start(args, fmt);
 
-	/* zbx_vsnprintf_check_len() cannot return negative result */
-	len = (size_t)zbx_vsnprintf_check_len(fmt, args) + 1;
+	len = zbx_vsnprintf_check_len(fmt, args) + 1;
 
 	va_end(args);