diff --git a/configure b/configure
index 5d95672..26f60a7 100755
--- a/configure
+++ b/configure
@@ -125,6 +125,7 @@ debug=no
 warnings=no
 shared=yes
 static=yes
+wrapper=auto
 
 for arg ; do
 case "$arg" in
@@ -199,27 +200,35 @@ exit 1
 fi
 
 #
-# Only build musl-gcc wrapper if toolchain does not already target musl
+# Need to know if the compiler is gcc to decide whether to build the
+# musl-gcc wrapper, and for critical bug detection in some gcc versions.
 #
-if test -z "$wrapper" ; then
 printf "checking whether compiler is gcc... "
 if fnmatch '*gcc\ version*' "$($CC -v 2>&1)" ; then
-echo yes
+cc_is_gcc=yes
+else
+cc_is_gcc=no
+fi
+echo "$cc_is_gcc"
+
+#
+# Only build musl-gcc wrapper if toolchain does not already target musl
+#
+if test "$wrapper" = auto ; then
 printf "checking whether to build musl-gcc wrapper... "
+if test "$cc_is_gcc" = yes ; then
 wrapper=yes
 while read line ; do
 case "$line" in */ld-musl-*) wrapper=no ;; esac
 done <<EOF
 $($CC -dumpspecs)
 EOF
-echo $wrapper
 else
-echo no
+wrapper=no
 fi
+echo "$wrapper"
 fi
 
-
-
 #
 # Find the target architecture
 #
@@ -484,6 +493,27 @@ printf "no\n"
 fail "$0: error: unsupported long double type"
 fi
 
+#
+# Check for known bug in GCC 4.9.0 that results in a broken libc.
+#
+if test "$cc_is_gcc" = yes ; then
+printf "checking for gcc constant folding bug with weak aliases... "
+echo 'static int x = 0;' > "$tmpc"
+echo 'extern int y __attribute__((__weak__, __alias__("x")));' >> "$tmpc"
+echo 'extern int should_appear;' >> "$tmpc"
+echo 'int foo() { return y ? should_appear : 0; }' >> "$tmpc"
+case "$($CC $CFLAGS_C99FSE -I./arch/$ARCH -I./include \
+  $CPPFLAGS $CFLAGS_AUTO $CFLAGS -S -o - "$tmpc" 2>/dev/null)" in
+*should_appear*)
+printf "no\n"
+;;
+*)
+printf "yes\n"
+fail "$0: error: broken compiler; try CFLAGS=-fno-toplevel-reorder"
+;;
+esac
+fi
+
 printf "creating config.mak... "
 
 cmdline=$(quote "$0")