diff --git a/fesvr/htif.cc b/fesvr/htif.cc
index a2477c1e..73f47f4b 100644
--- a/fesvr/htif.cc
+++ b/fesvr/htif.cc
@@ -65,14 +65,14 @@ htif_t::htif_t(int argc, char** argv) : htif_t()
 htif_t::htif_t(const std::vector<std::string>& args) : htif_t()
 {
   int argc = args.size() + 1;
-  char * argv[argc];
+  std::vector<char*>argv(argc);
   argv[0] = (char *) "htif";
   for (unsigned int i = 0; i < args.size(); i++) {
     argv[i+1] = (char *) args[i].c_str();
   }
   //Set line size as 16 by default.
   line_size = 16;
-  parse_arguments(argc, argv);
+  parse_arguments(argc, &argv[0]);
   register_devices();
 }
 
@@ -253,11 +253,10 @@ void htif_t::stop()
 
 void htif_t::clear_chunk(addr_t taddr, size_t len)
 {
-  char zeros[chunk_max_size()];
-  memset(zeros, 0, chunk_max_size());
+  std::vector<uint8_t> zeros(chunk_max_size(), 0);
 
   for (size_t pos = 0; pos < len; pos += chunk_max_size())
-    write_chunk(taddr + pos, std::min(len - pos, chunk_max_size()), zeros);
+    write_chunk(taddr + pos, std::min(len - pos, chunk_max_size()), &zeros[0]);
 }
 
 int htif_t::run()
diff --git a/fesvr/memif.cc b/fesvr/memif.cc
index e56bd943..59938b91 100644
--- a/fesvr/memif.cc
+++ b/fesvr/memif.cc
@@ -12,10 +12,10 @@ void memif_t::read(addr_t addr, size_t len, void* bytes)
   if (len && (addr & (align-1)))
   {
     size_t this_len = std::min(len, align - size_t(addr & (align-1)));
-    uint8_t chunk[align];
+    std::vector<uint8_t> chunk(align);
 
-    cmemif->read_chunk(addr & ~(align-1), align, chunk);
-    memcpy(bytes, chunk + (addr & (align-1)), this_len);
+    cmemif->read_chunk(addr & ~(align-1), align, &chunk[0]);
+    memcpy(bytes, &chunk[addr & (align-1)], this_len);
 
     bytes = (char*)bytes + this_len;
     addr += this_len;
@@ -26,10 +26,10 @@ void memif_t::read(addr_t addr, size_t len, void* bytes)
   {
     size_t this_len = len & (align-1);
     size_t start = len - this_len;
-    uint8_t chunk[align];
+    std::vector<uint8_t> chunk(align);
 
-    cmemif->read_chunk(addr + start, align, chunk);
-    memcpy((char*)bytes + start, chunk, this_len);
+    cmemif->read_chunk(addr + start, align, &chunk[0]);
+    memcpy((char*)bytes + start, &chunk[0], this_len);
 
     len -= this_len;
   }
@@ -45,11 +45,11 @@ void memif_t::write(addr_t addr, size_t len, const void* bytes)
   if (len && (addr & (align-1)))
   {
     size_t this_len = std::min(len, align - size_t(addr & (align-1)));
-    uint8_t chunk[align];
+    std::vector<uint8_t> chunk(align);
 
-    cmemif->read_chunk(addr & ~(align-1), align, chunk);
-    memcpy(chunk + (addr & (align-1)), bytes, this_len);
-    cmemif->write_chunk(addr & ~(align-1), align, chunk);
+    cmemif->read_chunk(addr & ~(align-1), align, &chunk[0]);
+    memcpy(&chunk[addr & (align-1)], bytes, this_len);
+    cmemif->write_chunk(addr & ~(align-1), align, &chunk[0]);
 
     bytes = (char*)bytes + this_len;
     addr += this_len;
@@ -60,11 +60,11 @@ void memif_t::write(addr_t addr, size_t len, const void* bytes)
   {
     size_t this_len = len & (align-1);
     size_t start = len - this_len;
-    uint8_t chunk[align];
+    std::vector<uint8_t> chunk(align);
 
-    cmemif->read_chunk(addr + start, align, chunk);
-    memcpy(chunk, (char*)bytes + start, this_len);
-    cmemif->write_chunk(addr + start, align, chunk);
+    cmemif->read_chunk(addr + start, align, &chunk[0]);
+    memcpy(&chunk[0], (char*)bytes + start, this_len);
+    cmemif->write_chunk(addr + start, align, &chunk[0]);
 
     len -= this_len;
   }