diff --git a/lib/dictBuilder/cover.c b/lib/dictBuilder/cover.c
index c8bee4e2..089f077c 100644
--- a/lib/dictBuilder/cover.c
+++ b/lib/dictBuilder/cover.c
@@ -28,7 +28,7 @@
 /*-*************************************
 *  Constants
 ***************************************/
-#define COVER_MAX_SAMPLES_SIZE ((U32)-1)
+#define COVER_MAX_SAMPLES_SIZE (sizeof(size_t) == 8 ? ((U32)-1) : ((U32)1 GB))
 
 /*-*************************************
 *  Console display
@@ -500,7 +500,9 @@ static int COVER_ctx_init(COVER_ctx_t *ctx, const void *samplesBuffer,
   const size_t totalSamplesSize = COVER_sum(samplesSizes, nbSamples);
   /* Checks */
   if (totalSamplesSize < d ||
-      totalSamplesSize > (size_t)COVER_MAX_SAMPLES_SIZE) {
+      totalSamplesSize >= (size_t)COVER_MAX_SAMPLES_SIZE) {
+    DISPLAYLEVEL(1, "Total samples size is too large, maximum size is %u MB\n",
+                 (COVER_MAX_SAMPLES_SIZE >> 20));
     return 0;
   }
   /* Zero the context */
@@ -518,6 +520,7 @@ static int COVER_ctx_init(COVER_ctx_t *ctx, const void *samplesBuffer,
   /* The offsets of each file */
   ctx->offsets = (size_t *)malloc((nbSamples + 1) * sizeof(size_t));
   if (!ctx->suffix || !ctx->dmerAt || !ctx->offsets) {
+    DISPLAYLEVEL(1, "Failed to allocate scratch buffers\n");
     COVER_ctx_destroy(ctx);
     return 0;
   }
@@ -651,7 +654,6 @@ ZDICTLIB_API size_t COVER_trainFromBuffer(
   /* Initialize context and activeDmers */
   if (!COVER_ctx_init(&ctx, samplesBuffer, samplesSizes, nbSamples,
                       parameters.d)) {
-    DISPLAYLEVEL(1, "Failed to initialize context\n");
     return ERROR(GENERIC);
   }
   if (!COVER_map_init(&activeDmers, parameters.k - parameters.d + 1)) {
diff --git a/lib/dictBuilder/zdict.h b/lib/dictBuilder/zdict.h
index b99990c3..1b3bcb5b 100644
--- a/lib/dictBuilder/zdict.h
+++ b/lib/dictBuilder/zdict.h
@@ -108,6 +108,7 @@ typedef struct {
     The resulting dictionary will be saved into `dictBuffer`.
     @return : size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)
               or an error code, which can be tested with ZDICT_isError().
+    Note : COVER_trainFromBuffer() requires about 9 bytes of memory for each input byte.
     Tips : In general, a reasonable dictionary has a size of ~ 100 KB.
            It's obviously possible to target smaller or larger ones, just by specifying different `dictBufferCapacity`.
            In general, it's recommended to provide a few thousands samples, but this can vary a lot.
@@ -131,6 +132,7 @@ ZDICTLIB_API size_t COVER_trainFromBuffer(void* dictBuffer, size_t dictBufferCap
     @return : size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)
               or an error code, which can be tested with ZDICT_isError().
               On success `*parameters` contains the parameters selected.
+    Note : COVER_optimizeTrainFromBuffer() requires about 9 bytes of memory for each input byte.
 */
 ZDICTLIB_API size_t COVER_optimizeTrainFromBuffer(void* dictBuffer, size_t dictBufferCapacity,
                                      const void* samplesBuffer, const size_t *samplesSizes, unsigned nbSamples,
diff --git a/programs/dibio.c b/programs/dibio.c
index 33c0250c..5ef202c8 100644
--- a/programs/dibio.c
+++ b/programs/dibio.c
@@ -235,7 +235,8 @@ int DiB_trainFromFiles(const char* dictFileName, unsigned maxDictSize,
     void* const dictBuffer = malloc(maxDictSize);
     size_t* const fileSizes = (size_t*)malloc(nbFiles * sizeof(size_t));
     unsigned long long const totalSizeToLoad = DiB_getTotalCappedFileSize(fileNamesTable, nbFiles);
-    size_t const maxMem =  DiB_findMaxMem(totalSizeToLoad * MEMMULT) / MEMMULT;
+    size_t const memMult = params ? MEMMULT : COVER_MEMMULT;
+    size_t const maxMem =  DiB_findMaxMem(totalSizeToLoad * memMult) / memMult;
     size_t benchedSize = (size_t) MIN ((unsigned long long)maxMem, totalSizeToLoad);
     void* const srcBuffer = malloc(benchedSize+NOISELENGTH);
     int result = 0;