diff --git a/ChangeLog b/ChangeLog
index d50df121..663e711c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -10,7 +10,6 @@ module; fall back to Javascript on these.
 counterpart.
  - Added a workaround for Visual Studio 2010 bug causing CPU features
 not to be detected.
- - The library now enables compilation with retpoline by default.
  - Portability improvements.
  - Test vectors from Project Wycheproof have been added.
  - New low-level APIs for arithmetic mod the order of the prime order group:
diff --git a/configure.ac b/configure.ac
index d4078d71..addf47bf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -149,6 +149,17 @@ AC_ARG_WITH(ctgrind,
   ])
 ])
 
+AC_ARG_ENABLE(retpoline,
+[AS_HELP_STRING(--enable-retpoline,Use return trampolines for indirect calls)],
+[AS_IF([test "x$enableval" = "xyes"], [
+  AX_CHECK_COMPILE_FLAG([-mindirect-branch=thunk-inline],
+    [CFLAGS="$CFLAGS -mindirect-branch=thunk-inline"],
+    [AX_CHECK_COMPILE_FLAG([-mretpoline], [CFLAGS="$CFLAGS -mretpoline"])]
+  )
+  AX_CHECK_COMPILE_FLAG([-mindirect-branch-register])
+  ])
+])
+
 ENABLE_CWFLAGS=no
 AC_ARG_ENABLE(debug,
 [AS_HELP_STRING(--enable-debug,For maintainers only - please do not use)],
@@ -197,13 +208,6 @@ AC_CHECK_DEFINE([_FORTIFY_SOURCE], [], [
     [CPPFLAGS="$CPPFLAGS -D_FORTIFY_SOURCE=2"])
 ])
 
-AS_IF([test "x$EMSCRIPTEN" = "x" -a "$host_os" != "pnacl"], [
-  AX_CHECK_COMPILE_FLAG([-mindirect-branch=thunk],
-    [CFLAGS="$CFLAGS -mindirect-branch=thunk"],
-    [AX_CHECK_COMPILE_FLAG([-mretpoline], [CFLAGS="$CFLAGS -mretpoline"])]
-  )
-])
-
 AX_CHECK_COMPILE_FLAG([-fvisibility=hidden],
   [CFLAGS="$CFLAGS -fvisibility=hidden"])