diff --git a/headers/readosm_protobuf.h b/headers/readosm_protobuf.h
index 0c3b897abae9694c20dbd58cdc52988f34197061..3c08e8332f08e3398238aaaeeabaa7e47fc8bb57 100644
--- a/headers/readosm_protobuf.h
+++ b/headers/readosm_protobuf.h
@@ -168,10 +168,10 @@ typedef struct readosm_uint32_struct
 typedef struct readosm_uint32_packed_struct
 {
 /* a PBF uint32 packed object */
-    readosm_uint32 *first;
-    readosm_uint32 *last;
-    int count;
     unsigned int *values;
+    unsigned int *next;
+    int count;
+    int max;
 } readosm_uint32_packed;
 
 typedef struct readosm_int32_struct
diff --git a/src/protobuf.c b/src/protobuf.c
index 03f5b4bd7cbee5a21de2f15bd9868e24f3f126b2..a38533d826452c6f67b54aba0b71b535e6bd37b2 100644
--- a/src/protobuf.c
+++ b/src/protobuf.c
@@ -252,70 +252,38 @@ static void
 init_uint32_packed (readosm_uint32_packed * packed)
 {
 /* initialing an empty PBF uint32 packed object */
-    packed->first = NULL;
-    packed->last = NULL;
+    packed->max = 128;
+    packed->values = malloc(packed->max * sizeof(unsigned int));
+    packed->next = packed->values;
     packed->count = 0;
-    packed->values = NULL;
 }
 
 static void
 append_uint32_packed (readosm_uint32_packed * packed, unsigned int val)
 {
 /* appending an uint32 value to a PBF packed object */
-    readosm_uint32 *value = malloc (sizeof (readosm_uint32));
-    value->value = val;
-    value->next = NULL;
-    if (packed->first == NULL)
-	packed->first = value;
-    if (packed->last != NULL)
-	packed->last->next = value;
-    packed->last = value;
+    if (packed->count == packed->max) {
+        packed->max *= 2;
+        packed->values = realloc(packed->values, packed->max * sizeof(unsigned int));
+        packed->next = packed->values + packed->count;
+    }
+    *(packed->next++) = val;
+    packed->count++;
 }
 
 static void
 array_from_uint32_packed (readosm_uint32_packed * packed)
 {
-/* creating an array supporting an uint32 packed object */
-    int i;
-    readosm_uint32 *value = packed->first;
-    while (value != NULL)
-      {
-	  /* counting how many values are into the packed list */
-	  packed->count++;
-	  value = value->next;
-      }
-    if (packed->count <= 0)
-	return;
-
-/* allocating the array */
-    packed->values = malloc (sizeof (unsigned int) * packed->count);
-    i = 0;
-    value = packed->first;
-    while (value != NULL)
-      {
-	  /* setting up array values */
-	  *(packed->values + i) = value->value;
-	  i++;
-	  value = value->next;
-      }
 }
 
 static void
 finalize_uint32_packed (readosm_uint32_packed * packed)
 {
 /* cleaning any memory allocation for an uint32 packed object */
-    readosm_uint32 *value;
-    readosm_uint32 *value_n;
-    value = packed->first;
-    while (value)
-      {
-	  value_n = value->next;
-	  free (value);
-	  value = value_n;
-      }
     if (packed->values)
 	free (packed->values);
-
+    packed->values = packed->next = NULL;
+    packed->max = packed->count = 0;
 }
 
 static void
@@ -1108,13 +1076,7 @@ parse_pbf_node_infos (readosm_packed_infos * packed_infos,
 		     variant.pointer + variant.length - 1,
 		     variant.little_endian_cpu))
 		    goto error;
-		count = 0;
-		pu32 = packed_u32.first;
-		while (pu32)
-		  {
-		      count++;
-		      pu32 = pu32->next;
-		  }
+		count = packed_u32.count;
 		packed_infos->ver_count = count;
 		if (packed_infos->versions != NULL)
 		  {
@@ -1124,13 +1086,9 @@ parse_pbf_node_infos (readosm_packed_infos * packed_infos,
 		if (count > 0)
 		  {
 		      packed_infos->versions = malloc (sizeof (int) * count);
-		      count = 0;
-		      pu32 = packed_u32.first;
-		      while (pu32)
+                      for (int kk = 0; kk < count; kk++)
 			{
-			    *(packed_infos->versions + count) = pu32->value;
-			    count++;
-			    pu32 = pu32->next;
+			    *(packed_infos->versions + kk) = packed_u32.values[kk];
 			}
 		  }
 		reset_uint32_packed (&packed_u32);