diff --git a/lib/compress/zstdmt_compress.h b/lib/compress/zstdmt_compress.h
index 91b489b9cb4..acd4d12438c 100644
--- a/lib/compress/zstdmt_compress.h
+++ b/lib/compress/zstdmt_compress.h
@@ -32,8 +32,8 @@
 #ifndef ZSTDMT_JOBSIZE_MIN   /* a different value can be selected at compile time */
 #  define ZSTDMT_JOBSIZE_MIN (512 KB)
 #endif
-#define ZSTDMT_JOBLOG_MAX   (MEM_32bits() ? 29 : 30)
-#define ZSTDMT_JOBSIZE_MAX  (MEM_32bits() ? (512 MB) : (1024 MB))
+#define ZSTDMT_JOBLOG_MAX   (MEM_32bits() ? 28 : 30)
+#define ZSTDMT_JOBSIZE_MAX  (MEM_32bits() ? (256 MB) : (1024 MB))
 
 
 /* ========================================================
diff --git a/tests/fuzzer.c b/tests/fuzzer.c
index 7b7c9d66631..dc587bb2c74 100644
--- a/tests/fuzzer.c
+++ b/tests/fuzzer.c
@@ -3907,6 +3907,19 @@ static int basicUnitTests(U32 const seed, double compressibility)
         }
     }
 
+    DISPLAYLEVEL(3, "test%3i : job size bounds match architecture : ", testNb++);
+    {   ZSTD_bounds const bounds = ZSTD_cParam_getBounds(ZSTD_c_jobSize);
+#ifdef ZSTD_MULTITHREAD
+        int const expectedJobSizeMax = MEM_32bits() ? (256 MB) : (1024 MB);
+#else
+        int const expectedJobSizeMax = 0;
+#endif
+        CHECK_Z(bounds.error);
+        if (bounds.lowerBound != 0) goto _output_error;
+        if (bounds.upperBound != expectedJobSizeMax) goto _output_error;
+    }
+    DISPLAYLEVEL(3, "OK \n");
+
     /* advanced parameters for decompression */
     {   ZSTD_DCtx* const dctx = ZSTD_createDCtx();
         assert(dctx != NULL);