diff --git a/src/libslic3r/GCode/PostProcessor.cpp b/src/libslic3r/GCode/PostProcessor.cpp
index c434aa5603..0e5929205b 100644
--- a/src/libslic3r/GCode/PostProcessor.cpp
+++ b/src/libslic3r/GCode/PostProcessor.cpp
@@ -16,7 +16,9 @@
 
 // The standard Windows includes.
 #define WIN32_LEAN_AND_MEAN
+#ifndef NOMINMAX
 #define NOMINMAX
+#endif
 #include <Windows.h>
 #include <shellapi.h>
 
diff --git a/src/libslic3r/Preset.cpp b/src/libslic3r/Preset.cpp
index 6eeb0cfca9..906b4c76b6 100644
--- a/src/libslic3r/Preset.cpp
+++ b/src/libslic3r/Preset.cpp
@@ -7,7 +7,9 @@
 
 #ifdef _MSC_VER
     #define WIN32_LEAN_AND_MEAN
+#ifndef NOMINMAX
     #define NOMINMAX
+#endif
     #include <Windows.h>
 #endif /* _MSC_VER */
 
diff --git a/tests/libslic3r/test_png_io.cpp b/tests/libslic3r/test_png_io.cpp
index e8229b7163..97fa064254 100644
--- a/tests/libslic3r/test_png_io.cpp
+++ b/tests/libslic3r/test_png_io.cpp
@@ -1,4 +1,7 @@
+#ifndef NOMINMAX
 #define NOMINMAX
+#endif
+
 #include <catch2/catch.hpp>
 
 #include <numeric>