diff --git a/lib/system/io.nim b/lib/system/io.nim
index 62722140fd78b..b6e82d7a05442 100644
--- a/lib/system/io.nim
+++ b/lib/system/io.nim
@@ -610,7 +610,7 @@ when declared(stdout):
       android_log_print(ANDROID_LOG_VERBOSE, "nim", s)
     else:
       # flockfile deadlocks some versions of Android 5.x.x
-      when not defined(windows) and not defined(android) and not defined(nintendoswitch):
+      when not defined(windows) and not defined(android) and not defined(nintendoswitch) and hostOS != "ansic":
         proc flockfile(f: File) {.importc, nodecl.}
         proc funlockfile(f: File) {.importc, nodecl.}
         flockfile(stdout)
@@ -624,7 +624,7 @@ when declared(stdout):
       const linefeed = "\n"
       discard c_fwrite(linefeed.cstring, linefeed.len, 1, stdout)
       discard c_fflush(stdout)
-      when not defined(windows) and not defined(android) and not defined(nintendoswitch):
+      when not defined(windows) and not defined(android) and not defined(nintendoswitch) and hostOS != "ansic":
         funlockfile(stdout)
       when defined(windows) and compileOption("threads"):
         releaseSys echoLock