diff --git a/process.c b/process.c
index 3c5f030b65..be2342abe2 100644
--- a/process.c
+++ b/process.c
@@ -1133,7 +1133,6 @@ static rb_pid_t
 proc_spawn_v(char **argv, char *prog)
 {
     char fbuf[MAXPATHLEN];
-    char *extension;
     rb_pid_t status;
 
     if (!prog)