diff --git a/nimgen.nim b/nimgen.nim
index 6f6998f..3c59524 100644
--- a/nimgen.nim
+++ b/nimgen.nim
@@ -54,7 +54,7 @@ proc execProc(cmd: string): string =
         quit(1)
 
 proc extractZip(zipfile: string) =
-    var cmd = "unzip $#"
+    var cmd = "unzip -o $#"
     if defined(Windows):
         cmd = "powershell -nologo -noprofile -command \"& { Add-Type -A 'System.IO.Compression.FileSystem'; [IO.Compression.ZipFile]::ExtractToDirectory('$#', '.'); }\""