diff --git a/tests/zstreamtest.c b/tests/zstreamtest.c
index 3053638..97fbaa1 100644
--- a/tests/zstreamtest.c
+++ b/tests/zstreamtest.c
@@ -58,7 +58,7 @@
             if ((FUZ_GetClockSpan(g_displayClock) > g_refreshRate) || (g_displayLevel>=4)) \
             { g_displayClock = clock(); DISPLAY(__VA_ARGS__); \
             if (g_displayLevel>=4) fflush(stdout); } }
-static const clock_t g_refreshRate = CLOCKS_PER_SEC * 15 / 100;
+static const clock_t g_refreshRate = CLOCKS_PER_SEC / 6;
 static clock_t g_displayClock = 0;
 
 static clock_t g_clockTime = 0;
@@ -118,8 +118,7 @@
 
 static int basicUnitTests(U32 seed, double compressibility, ZSTD_customMem customMem)
 {
-    int testResult = 0;
-    size_t CNBufferSize = COMPRESSIBLE_NOISE_LENGTH;
+    size_t const CNBufferSize = COMPRESSIBLE_NOISE_LENGTH;
     void* CNBuffer = malloc(CNBufferSize);
     size_t const skippableFrameSize = 11;
     size_t const compressedBufferSize = (8 + skippableFrameSize) + ZSTD_compressBound(COMPRESSIBLE_NOISE_LENGTH);
@@ -127,6 +126,7 @@
     size_t const decodedBufferSize = CNBufferSize;
     void* decodedBuffer = malloc(decodedBufferSize);
     size_t cSize;
+    int testResult = 0;
     U32 testNb=0;
     ZSTD_CStream* zc = ZSTD_createCStream_advanced(customMem);
     ZSTD_DStream* zd = ZSTD_createDStream_advanced(customMem);
@@ -437,7 +437,7 @@
         {   U32 const testLog = FUZ_rand(&lseed) % maxSrcLog;
             U32 const cLevel = (FUZ_rand(&lseed) % (ZSTD_maxCLevel() - (testLog/3))) + 1;
             maxTestSize = FUZ_rLogLength(&lseed, testLog);
-            dictSize  = (FUZ_rand(&lseed)==1) ? FUZ_randomLength(&lseed, maxSampleLog) : 0;
+            dictSize  = ((FUZ_rand(&lseed)&63)==1) ? FUZ_randomLength(&lseed, maxSampleLog) : 0;
             /* random dictionary selection */
             {   size_t const dictStart = FUZ_rand(&lseed) % (srcBufferSize - dictSize);
                 dict = srcBuffer + dictStart;
@@ -446,7 +446,7 @@
                 params.fParams.checksumFlag = FUZ_rand(&lseed) & 1;
                 params.fParams.noDictIDFlag = FUZ_rand(&lseed) & 1;
                 {   size_t const initError = ZSTD_initCStream_advanced(zc, dict, dictSize, params, 0);
-                    CHECK (ZSTD_isError(initError),"init error : %s", ZSTD_getErrorName(initError));
+                    CHECK (ZSTD_isError(initError),"ZSTD_initCStream_advanced error : %s", ZSTD_getErrorName(initError));
         }   }   }
 
         /* multi-segments compression test */