diff --git a/ext/ttml/gstttmlrender.c b/ext/ttml/gstttmlrender.c
index b6a63b5bf5..6c1689454a 100644
--- a/ext/ttml/gstttmlrender.c
+++ b/ext/ttml/gstttmlrender.c
@@ -1841,7 +1841,9 @@ gst_ttml_render_split_block (UnifiedBlock * block, GPtrArray * char_ranges)
   gint i;
 
   for (i = 0; i < char_ranges->len; ++i) {
-    gint index, first_offset, last_offset;
+    gint index;
+    gint first_offset = 0;
+    gint last_offset = 0;
     CharRange *range = g_ptr_array_index (char_ranges, i);
     UnifiedBlock *clone = gst_ttml_render_unified_block_copy (block);
     UnifiedElement *ue;
@@ -1855,6 +1857,12 @@ gst_ttml_render_split_block (UnifiedBlock * block, GPtrArray * char_ranges)
     GST_CAT_LOG (ttmlrender_debug, "Last char in range is in element %d",
         index);
 
+    if (index < 0) {
+      GST_CAT_WARNING (ttmlrender_debug, "Range end not found in block text.");
+      gst_ttml_render_unified_block_free (clone);
+      continue;
+    }
+
     /* Remove elements that are after the one that contains the range end. */
     GST_CAT_LOG (ttmlrender_debug, "There are %d elements in cloned block.",
         gst_ttml_render_unified_block_element_count (clone));
@@ -1869,6 +1877,13 @@ gst_ttml_render_split_block (UnifiedBlock * block, GPtrArray * char_ranges)
     GST_CAT_LOG (ttmlrender_debug, "First char in range is in element %d",
         index);
 
+    if (index < 0) {
+      GST_CAT_WARNING (ttmlrender_debug,
+          "Range start not found in block text.");
+      gst_ttml_render_unified_block_free (clone);
+      continue;
+    }
+
     /* Remove elements that are before the one that contains the range start. */
     while (index > 0) {
       GST_CAT_LOG (ttmlrender_debug, "Removing first element in cloned block");