diff --git a/src/libslic3r/libslic3r.h b/src/libslic3r/libslic3r.h
index 5fd2fafc1b..54344c6181 100644
--- a/src/libslic3r/libslic3r.h
+++ b/src/libslic3r/libslic3r.h
@@ -167,7 +167,7 @@ static inline T lerp(const T& a, const T& b, Number t)
 template <typename Number>
 static inline bool is_approx(Number value, Number test_value)
 {
-    return std::abs(double(value) - double(test_value)) < double(EPSILON);
+    return std::fabs(double(value) - double(test_value)) < double(EPSILON);
 };
 
 } // namespace Slic3r