diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 3467467383..f5ae5250c6 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2018-05-10  Tom Tromey  <tom@tromey.com>
+
+	* configure: Rebuild.
+	* warning.m4 (AM_GDB_WARNINGS): Use -Wimplicit-fallthrough=3.
+
 2018-05-10  Joel Brobecker  <brobecker@adacore.com>
 
 	PR server/23158:
diff --git a/gdb/configure b/gdb/configure
index 0eec780bd1..4186f7e160 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -15367,7 +15367,7 @@ build_warnings="-Wall -Wpointer-arith \
 -Wno-mismatched-tags \
 -Wno-error=deprecated-register \
 -Wsuggest-override \
--Wimplicit-fallthrough \
+-Wimplicit-fallthrough=3 \
 -Wduplicated-cond"
 
 case "${host}" in
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 9ead1220a7..36915cf736 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,7 @@
+2018-05-10  Tom Tromey  <tom@tromey.com>
+
+	* configure: Rebuild.
+
 2018-05-10  Joel Brobecker  <brobecker@adacore.com>
 
 	PR server/23158:
diff --git a/gdb/gdbserver/configure b/gdb/gdbserver/configure
index ac61ba3543..b2e2e8f955 100755
--- a/gdb/gdbserver/configure
+++ b/gdb/gdbserver/configure
@@ -7174,7 +7174,7 @@ build_warnings="-Wall -Wpointer-arith \
 -Wno-mismatched-tags \
 -Wno-error=deprecated-register \
 -Wsuggest-override \
--Wimplicit-fallthrough \
+-Wimplicit-fallthrough=3 \
 -Wduplicated-cond"
 
 case "${host}" in
diff --git a/gdb/warning.m4 b/gdb/warning.m4
index cb23472ec6..632cc214ac 100644
--- a/gdb/warning.m4
+++ b/gdb/warning.m4
@@ -44,7 +44,7 @@ build_warnings="-Wall -Wpointer-arith \
 -Wno-mismatched-tags \
 -Wno-error=deprecated-register \
 -Wsuggest-override \
--Wimplicit-fallthrough \
+-Wimplicit-fallthrough=3 \
 -Wduplicated-cond"
 
 case "${host}" in