diff --git a/src/libslic3r/Support/TreeSupportCommon.hpp b/src/libslic3r/Support/TreeSupportCommon.hpp
index 1dc8b309d6..50ca626fa3 100644
--- a/src/libslic3r/Support/TreeSupportCommon.hpp
+++ b/src/libslic3r/Support/TreeSupportCommon.hpp
@@ -619,7 +619,7 @@ static constexpr const bool polygons_strictly_simple = false;
 
 inline double tiny_area_threshold() { return sqr(scaled<double>(0.001)); }
 
-void tree_supports_show_error(std::string_view message, bool critical)
+inline void tree_supports_show_error(std::string_view message, bool critical)
 { // todo Remove!  ONLY FOR PUBLIC BETA!!
     printf("Error: %s, critical: %d\n", message.data(), int(critical));
 #ifdef TREE_SUPPORT_SHOW_ERRORS_WIN32