diff --git a/ChangeLog b/ChangeLog
index 9c0b0124f..0da6bb1a8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2018-08-10  Werner Lemberg  <wl@gnu.org>
+
+	Fix clang warnings.
+
+	* src/base/ftdebug.c (ft_trace_level_enabled,
+	ft_trace_level_disabled): Add `static' keyword.
+
 2018-08-09  Alexei Podtelezhnikov  <apodtele@gmail.com>
 
 	[raster, smooth] Reinstate bitmap size limits.
diff --git a/src/base/ftdebug.c b/src/base/ftdebug.c
index 8c7e51c85..19b0058d3 100644
--- a/src/base/ftdebug.c
+++ b/src/base/ftdebug.c
@@ -102,10 +102,10 @@
 
   /* array of trace levels, initialized to 0; */
   /* this gets adjusted at run-time           */
-  int  ft_trace_levels_enabled[trace_count];
+  static int  ft_trace_levels_enabled[trace_count];
 
   /* array of trace levels, always initialized to 0 */
-  int  ft_trace_levels_disabled[trace_count];
+  static int  ft_trace_levels_disabled[trace_count];
 
   /* a pointer to either `ft_trace_levels_enabled' */
   /* or `ft_trace_levels_disabled'                 */