diff --git a/src/libslic3r/SLA/SLAAutoSupports.cpp b/src/libslic3r/SLA/SLAAutoSupports.cpp
index 9b1c56e51..ca04b1bee 100644
--- a/src/libslic3r/SLA/SLAAutoSupports.cpp
+++ b/src/libslic3r/SLA/SLAAutoSupports.cpp
@@ -146,8 +146,8 @@ float SLAAutoSupports::get_required_density(float angle) const
 {
     // calculation would be density_0 * cos(angle). To provide one more degree of freedom, we will scale the angle
     // to get the user-set density for 45 deg. So it ends up as density_0 * cos(K * angle).
-    float K = 4*acos(m_config.density_at_45/m_config.density_at_horizontal) / M_PI;
-    return std::max(0., m_config.density_at_horizontal * cos(K*angle));
+    float K = 4.f * float(acos(m_config.density_at_45/m_config.density_at_horizontal) / M_PI);
+    return std::max(0.f, float(m_config.density_at_horizontal * cos(K*angle)));
 }