diff --git a/src/libslic3r/Format/3mf.cpp b/src/libslic3r/Format/3mf.cpp
index 9f4015913..1ca20bcba 100644
--- a/src/libslic3r/Format/3mf.cpp
+++ b/src/libslic3r/Format/3mf.cpp
@@ -1917,7 +1917,7 @@ namespace Slic3r {
             int max_id = faces.front()[0];
             for (const Vec3i& face : faces) {
                 for (const int tri_id : face) {
-                    if (tri_id < 0 || tri_id >= geometry.vertices.size()) {
+                    if (tri_id < 0 || tri_id >= int(geometry.vertices.size())) {
                         add_error("Found invalid vertex id");
                         return false;
                     }
diff --git a/src/libslic3r/Format/OBJ.cpp b/src/libslic3r/Format/OBJ.cpp
index 54c373ce3..3b05bb574 100644
--- a/src/libslic3r/Format/OBJ.cpp
+++ b/src/libslic3r/Format/OBJ.cpp
@@ -73,7 +73,7 @@ bool load_obj(const char *path, TriangleMesh *meshptr)
                     break;
                 } else {
                     assert(cnt < 4);
-                    if (vertex.coordIdx < 0 || vertex.coordIdx >= its.vertices.size()) {
+                    if (vertex.coordIdx < 0 || vertex.coordIdx >= int(its.vertices.size())) {
                         BOOST_LOG_TRIVIAL(error) << "load_obj: failed to parse " << path << ". The file contains invalid vertex index.";
                         return false;
                     }