diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 616a3d581..884a4e00d 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -389,6 +389,7 @@ size_t ZSTD_CCtxParam_setParameter(
         if (value == 0) return 0;
 #ifndef ZSTD_MULTITHREAD
         if (value > 1) return ERROR(parameter_unsupported);
+        return 0;
 #else
         return ZSTDMT_initializeCCtxParameters(params, value);
 #endif