diff --git a/c++/som/configuration.cpp b/c++/som/configuration.cpp
index 49d5f5826..9701520ba 100644
--- a/c++/som/configuration.cpp
+++ b/c++/som/configuration.cpp
@@ -115,9 +115,6 @@ configuration configuration::operator+(configuration const& c) const {
 }
 
 configuration& configuration::operator*=(double alpha) {
-  if(alpha < 0)
-    TRIQS_RUNTIME_ERROR
-        << "Cannot multiply a configuration by a negative number " << alpha;
   std::transform(rects.begin(), rects.end(), rects.begin(),
                  [&](rectangle const& r) { return r * alpha; });
   cache_ptr.invalidate_entry();
diff --git a/test/c++/configuration.cpp b/test/c++/configuration.cpp
index f4c11bb54..f1598960f 100644
--- a/test/c++/configuration.cpp
+++ b/test/c++/configuration.cpp
@@ -64,9 +64,6 @@ TEST(configuration, Detached) {
 TEST(configuration, Arithmetics) {
   EXPECT_PRINT(conf1_str + "," + conf2_str, conf1 + conf2);
 
-  EXPECT_THROW(-2.0 * conf1, triqs::runtime_error);
-  EXPECT_THROW(conf1 * (-2.0), triqs::runtime_error);
-
   EXPECT_PRINT("(c:-2, w:2.6, h:0.6),(c:1.3, w:2.6, h:1.2),(c:2, w:2.6, h:1.4)",
                2.0 * conf1);
   EXPECT_PRINT(