diff --git a/qemu/configure b/qemu/configure
index f049954c..fbea58a5 100755
--- a/qemu/configure
+++ b/qemu/configure
@@ -223,7 +223,11 @@ strip="${STRIP-${cross_prefix}strip}"
 ARFLAGS="${ARFLAGS-rv}"
 
 # default flags for all hosts
-QEMU_CFLAGS="-fno-strict-aliasing -fno-common $QEMU_CFLAGS"
+# We use -fwrapv to tell the compiler that we require a C dialect where
+# left shift of signed integers is well defined and has the expected
+# 2s-complement style results. (Both clang and gcc agree that it
+# provides these semantics.)
+QEMU_CFLAGS="-fno-strict-aliasing -fno-common -fwrapv $QEMU_CFLAGS"
 QEMU_CFLAGS="-Wall -Wundef -Wwrite-strings -Wmissing-prototypes $QEMU_CFLAGS"
 QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls $QEMU_CFLAGS"
 QEMU_CFLAGS="-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE $QEMU_CFLAGS"