diff --git a/src/samplefunctional.hh b/src/samplefunctional.hh
index e69d3bfa9129917447c8842702679905d2f63183..1aa0000e20398d69fd95be3439a78ffe257959f5 100644
--- a/src/samplefunctional.hh
+++ b/src/samplefunctional.hh
@@ -74,7 +74,7 @@ template <int dimension> class SampleFunctional {
                "semigradient): " << -(ret * pg)
             << " (coordinates of the restriction)" << std::endl;
     } else {
-      ret = project(smoothGradient(x), x);
+      ret = negative_projection(smoothGradient(x), x);
       dverb << "## Directional derivative (as per scalar product w/ "
                "semigradient): " << -(ret * ret)
             << " (coordinates of the restriction)" << std::endl;
@@ -110,7 +110,8 @@ template <int dimension> class SampleFunctional {
   }
 
   // No normalising is done!
-  SmallVector project(const SmallVector z, const SmallVector x) const {
+  SmallVector negative_projection(const SmallVector z,
+                                  const SmallVector x) const {
     SmallVector y = z;
     y.axpy(-(z * x) / x.two_norm2(), x);
     return y;