diff --git a/power/VcdParse.cc b/power/VcdParse.cc
index c1dcc642..071fcdf7 100644
--- a/power/VcdParse.cc
+++ b/power/VcdParse.cc
@@ -232,28 +232,15 @@ VcdParse::parseVarValues()
       reader_->varAppendValue(id, time_, char0);
     }
     else if (char0 == 'B') {
-      char char1 = toupper(token[1]);
-      if (char1 == 'X'
-          || char1 == 'U'
-          || char1 == 'Z') {
-        string id = getToken();
-        if (!reader_->varIdValid(id))
-          report_->fileError(806, filename_, stmt_line_,
-                             "unknown variable %s", id.c_str());
-        // Bus mixed 0/1/X/U not supported.
-        reader_->varAppendValue(id, time_, char1);
-      }
+      string bus_value = token.substr(1);
+      string id = getToken();
+      if (!reader_->varIdValid(id))
+        report_->fileError(807, filename_, stmt_line_,
+                           "unknown variable %s", id.c_str());
       else {
-        string bus_value = token.substr(1);
-        string id = getToken();
-        if (!reader_->varIdValid(id))
-          report_->fileError(807, filename_, stmt_line_,
-                             "unknown variable %s", id.c_str());
-        else {
-          // Reverse the bus value to match the bit order in the VCD file.
-          std::reverse(bus_value.begin(), bus_value.end());
-          reader_->varAppendBusValue(id, time_, bus_value);
-        }
+        // Reverse the bus value to match the bit order in the VCD file.
+        std::reverse(bus_value.begin(), bus_value.end());
+        reader_->varAppendBusValue(id, time_, bus_value);
       }
     }
     token = getToken();
diff --git a/power/VcdReader.cc b/power/VcdReader.cc
index 81874e0a..f208c8ad 100644
--- a/power/VcdReader.cc
+++ b/power/VcdReader.cc
@@ -335,8 +335,15 @@ VcdCountReader::varAppendBusValue(const string &id,
   if (itr != vcd_count_map_.end()) {
     VcdCounts &vcd_counts = itr->second;
     for (size_t bit_idx = 0; bit_idx < vcd_counts.size(); bit_idx++) {
-      char bit_value = bus_value[bit_idx];
+      char bit_value;
+      if (bus_value.size() == 1)
+        bit_value = bus_value[0];
+      else if  (bit_idx < bus_value.size())
+        bit_value = bus_value[bit_idx];
+      else
+        bit_value = '0';
       VcdCount &vcd_count = vcd_counts[bit_idx];
+      vcd_count.incrCounts(time, bit_value);
       if (debug_->check("read_vcd", 3)) {
         for (const Pin *pin : vcd_count.pins()) {
           debugPrint(debug_, "read_vcd", 3, "%s time %" PRIu64 " value %c",
@@ -345,7 +352,6 @@ VcdCountReader::varAppendBusValue(const string &id,
                      bit_value);
         }
       }
-      vcd_count.incrCounts(time, bit_value);
     }
   }
 }