diff --git a/libphobos/ChangeLog b/libphobos/ChangeLog
index 131d7f9168f..f1b76bb88d2 100644
--- a/libphobos/ChangeLog
+++ b/libphobos/ChangeLog
@@ -1,3 +1,8 @@
+2019-04-25  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
+
+	* m4/druntime/cpu.m4 (DRUNTIME_CPU_SOURCES): Quote brackets.
+	* configure: Regenerate.
+
 2019-04-25  Johannes Pfau  <johannespfau@gmail.com>
 
         * libdruntime/Makefile.am: Add emutls and gthread files.
diff --git a/libphobos/configure b/libphobos/configure
index 67fe34d7184..e2977b3cc74 100755
--- a/libphobos/configure
+++ b/libphobos/configure
@@ -14050,7 +14050,7 @@ fi
       powerpc64)
                druntime_target_cpu_parsed="powerpc64"
                ;;
-      i3456786|x86_64)
+      i[34567]86|x86_64)
                druntime_target_cpu_parsed="x86"
                ;;
   esac
diff --git a/libphobos/m4/druntime/cpu.m4 b/libphobos/m4/druntime/cpu.m4
index 4795edaa78d..aa5b5ea08fc 100644
--- a/libphobos/m4/druntime/cpu.m4
+++ b/libphobos/m4/druntime/cpu.m4
@@ -22,7 +22,7 @@ AC_DEFUN([DRUNTIME_CPU_SOURCES],
       powerpc64)
                druntime_target_cpu_parsed="powerpc64"
                ;;
-      i[34567]86|x86_64)
+      i[[34567]]86|x86_64)
                druntime_target_cpu_parsed="x86"
                ;;
   esac