diff --git a/configure.ac b/configure.ac
index a932568..cddac7b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -71,6 +71,12 @@ dnl Check for dl library (needed for GiNaC::compile).
 GINAC_EXCOMPILER
 AM_CONDITIONAL(CONFIG_EXCOMPILER, [test "x${CONFIG_EXCOMPILER}" = "xyes"])
 
+dnl Option to enable deterministic sorting
+AC_ARG_ENABLE(determinism,[AS_HELP_STRING([--enable-determinism],
+              [Enable deterministic term ordering @<:@default=no@:>@])],
+              [], [enable_determinism=no])
+test "x$enable_determinism" == xyes && AC_DEFINE(DETERMINISTIC_ORDERING,1,[deterministic sorting])
+
 dnl Check for utilities needed by the different kinds of documentation.
 dnl Documentation needs only be built when extending it, so never mind if it
 dnl cannot find those helpers:
diff --git a/ginac/hash_seed.h b/ginac/hash_seed.h
index 32b057f..db255e7 100644
--- a/ginac/hash_seed.h
+++ b/ginac/hash_seed.h
@@ -23,6 +23,14 @@
 #endif
 namespace GiNaC
 {
+#ifdef DETERMINISTIC_ORDERING
+static inline unsigned make_hash_seed(const std::type_info& tinfo)
+{
+	// deterministic ordering of different types is defined
+	// via typeid_this.before(typeid_other) in basic.cpp
+	return 0;
+}
+#else /* DETERMINISTIC_ORDERING */
 #ifndef GINAC_HASH_USE_MANGLED_NAME
 static inline unsigned make_hash_seed(const std::type_info& tinfo)
 {
@@ -32,13 +40,14 @@ static inline unsigned make_hash_seed(const std::type_info& tinfo)
 	unsigned v = golden_ratio_hash((p_int)mangled_name_ptr);
 	return v;
 }
-#else
+#else /* GINAC_HASH_USE_MANGLED_NAME */
 static unsigned make_hash_seed(const std::type_info& tinfo)
 {
 	const char* mangled_name = tinfo.name();
 	return crc32(mangled_name, std::strlen(mangled_name), 0);
 }
-#endif
+#endif /* GINAC_HASH_USE_MANGLED_NAME */
+#endif /* DETERMINISTIC_ORDERING */
 } // namespace GiNaC
 #endif /* GINAC_HASH_SEED_H */