diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e1ad84a4d2..5b048627c9 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2017-06-26  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* common/diagnostics.h (DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER):
+	New macro.
+	* ada-lex.l: Ignore deprecated register warnings.
+
 2017-06-25  Simon Marchi  <simon.marchi@ericsson.com>
 
 	* main.c (get_init_files): Replace "SYSTEM_GDBINIT +
diff --git a/gdb/ada-lex.l b/gdb/ada-lex.l
index 0825290214..fe97352d85 100644
--- a/gdb/ada-lex.l
+++ b/gdb/ada-lex.l
@@ -41,6 +41,14 @@ POSEXP  (e"+"?{NUM10})
 
 %{
 
+#include "common/diagnostics.h"
+
+/* Some old versions of flex generate code that uses the "register" keyword,
+   which clang warns about.  This was observed for example with flex 2.5.35,
+   as shipped with macOS 10.12.  */
+DIAGNOSTIC_PUSH
+DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER
+
 #define NUMERAL_WIDTH 256
 #define LONGEST_SIGN ((ULONGEST) 1 << (sizeof(LONGEST) * HOST_CHAR_BIT - 1))
 
@@ -648,3 +656,5 @@ dummy_function ada_flex_use[] =
 { 
   (dummy_function) yyunput
 };
+
+DIAGNOSTIC_POP
diff --git a/gdb/common/diagnostics.h b/gdb/common/diagnostics.h
index 5a63bfd8d4..35bacf25bb 100644
--- a/gdb/common/diagnostics.h
+++ b/gdb/common/diagnostics.h
@@ -33,8 +33,11 @@
 
 #ifdef __clang__
 # define DIAGNOSTIC_IGNORE_SELF_MOVE DIAGNOSTIC_IGNORE ("-Wself-move")
+# define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER \
+  DIAGNOSTIC_IGNORE ("-Wdeprecated-register")
 #else
 # define DIAGNOSTIC_IGNORE_SELF_MOVE
+# define DIAGNOSTIC_IGNORE_DEPRECATED_REGISTER
 #endif
 
 #endif /* COMMON_DIAGNOSTICS_H */