--- a/old-configure.in
+++ b/old-configure.in
@@ -1520,33 +1520,33 @@ case "$target" in
     case "$host_os" in
     cygwin*|msvc*|mks*)
         AC_MSG_ERROR([Using a Cygwin build environment is unsupported. Configure cannot check for presence of necessary headers. Please upgrade to MozillaBuild; see https://developer.mozilla.org/en/Windows_Build_Prerequisites.])
         ;;
     esac
 
     case "$target" in
     i*86-*)
-        if test "$HAVE_64BIT_BUILD"; then
+        if test "$HAVE_64BIT_BUILD" -a "$COMPILE_ENVIRONMENT"; then
             AC_MSG_ERROR([You are targeting i386 but using the 64-bit compiler.])
         fi
 
         if test -n "$GNU_CC"; then
             CFLAGS="$CFLAGS -mstackrealign -fno-keep-inline-dllexport"
             CXXFLAGS="$CXXFLAGS -mstackrealign -fno-keep-inline-dllexport"
             LDFLAGS="$LDFLAGS -Wl,--enable-stdcall-fixup -Wl,--large-address-aware"
         else
             DSO_LDOPTS="$DSO_LDOPTS -MACHINE:X86"
             LDFLAGS="$LDFLAGS -SAFESEH"
         fi
 
         AC_DEFINE(_X86_)
         ;;
     x86_64-*)
-        if test -z "$HAVE_64BIT_BUILD"; then
+        if test -z "$HAVE_64BIT_BUILD" -a "$COMPILE_ENVIRONMENT"; then
             AC_MSG_ERROR([You are targeting 64-bit but using the 32-bit compiler.])
         fi
         if test -n "$_WIN32_MSVC"; then
             DSO_LDOPTS="$DSO_LDOPTS -MACHINE:X64"
         fi
         AC_DEFINE(_AMD64_)
         ;;
     *)