diff --git a/src/lib.rs b/src/lib.rs
index bdd437a6..cfe5f63b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1945,8 +1945,15 @@ impl Build {
                     None => {
                         let features = self.getenv("CARGO_CFG_TARGET_FEATURE");
                         let features = features.as_deref().unwrap_or_default();
+                        let debug = self.get_debug();
                         if features.to_string_lossy().contains("crt-static") {
-                            "-MT"
+                            if debug {
+                                "-MTd"
+                            } else {
+                                "-MT"
+                            }
+                        } else if debug {
+                            "-MDd"
                         } else {
                             "-MD"
                         }