diff --git a/configure.ac b/configure.ac
index ef7cba0a..9f048312 100644
--- a/configure.ac
+++ b/configure.ac
@@ -70,6 +70,7 @@ TEST_AND_ADD_FLAGS([AM_CFLAGS], [C], [-Wmissing-declarations])
 TEST_AND_ADD_FLAGS([AM_CFLAGS], [C], [-Wmissing-prototypes])
 TEST_AND_ADD_FLAGS([AM_CFLAGS], [C], [-Wold-style-definition])
 TEST_AND_ADD_FLAGS([AM_CFLAGS], [C], [-Wshadow])
+TEST_AND_ADD_FLAGS([AM_CFLAGS], [C], [-Wunreachable-code])
 TEST_AND_ADD_FLAGS([AM_CFLAGS], [C], [-Wunused-but-set-variable])
 TEST_AND_ADD_FLAGS([AM_CFLAGS], [C], [-Wunused])
 TEST_AND_ADD_FLAGS([AM_CFLAGS], [C], [-Wvla])
@@ -464,6 +465,7 @@ AS_IF([test "x$enable_gif" != "xno"], [
       TEST_AND_ADD_FLAGS([AM_CXXFLAGS], [CXX], [-Wformat-security])
       TEST_AND_ADD_FLAGS([AM_CXXFLAGS], [CXX], [-Wmissing-declarations])
       TEST_AND_ADD_FLAGS([AM_CXXFLAGS], [CXX], [-Wshadow])
+      TEST_AND_ADD_FLAGS([AM_CXXFLAGS], [CXX], [-Wunreachable-code])
       TEST_AND_ADD_FLAGS([AM_CXXFLAGS], [CXX], [-Wunused-but-set-variable])
       TEST_AND_ADD_FLAGS([AM_CXXFLAGS], [CXX], [-Wunused])
       TEST_AND_ADD_FLAGS([AM_CXXFLAGS], [CXX], [-Wvla])