diff --git a/src/backends/packrat.c b/src/backends/packrat.c
index 91e4a09224cb03c4eac23d1713dbbc70941d6618..1941f1c9d3d97e492dd4b8bb078f91f7fce75aed 100644
--- a/src/backends/packrat.c
+++ b/src/backends/packrat.c
@@ -294,6 +294,7 @@ HParseResult *h_packrat_parse(HAllocator* mm__, const HParser* parser, HInputStr
   parse_state->lr_stack = h_slist_new(arena);
   parse_state->recursion_heads = h_hashtable_new(arena, pos_equal, pos_hash);
   parse_state->arena = arena;
+  parse_state->symbol_table = NULL;
   HParseResult *res = h_do_parse(parser, parse_state);
   h_slist_free(parse_state->lr_stack);
   h_hashtable_free(parse_state->recursion_heads);
diff --git a/src/backends/regex.c b/src/backends/regex.c
index c10c25890fd5bfdf5e3e9b37a64e988fd3010749..f26abfda67af76900010053c6a6003fad1df55e7 100644
--- a/src/backends/regex.c
+++ b/src/backends/regex.c
@@ -7,6 +7,8 @@
 
 #undef a_new
 #define a_new(typ, count) a_new_(arena, typ, count)
+#undef a_new0
+#define a_new0(typ, count) a_new0_(arena, typ, count)
 // Stack VM
 typedef enum HSVMOp_ {
   SVM_PUSH, // Push a mark. There is no VM insn to push an object.
@@ -67,13 +69,13 @@ void* h_rvm_run__m(HAllocator *mm__, HRVMProg *prog, const uint8_t* input, size_
     goto end;
 
   HSArray *heads_n = heads_a, *heads_p = heads_b;
-  uint8_t *insn_seen = a_new(uint8_t, prog->length); // 0 -> not seen, 1->processed, 2->queued
-  HRVMThread *ip_queue = a_new(HRVMThread, prog->length);
+  uint8_t *insn_seen = a_new0(uint8_t, prog->length); // 0 -> not seen, 1->processed, 2->queued
+  HRVMThread *ip_queue = a_new0(HRVMThread, prog->length);
   size_t ipq_top;
 
 #define THREAD ip_queue[ipq_top-1]
 #define PUSH_SVM(op_, arg_) do { \
-	  HRVMTrace *nt = a_new(HRVMTrace, 1); \
+	  HRVMTrace *nt = a_new0(HRVMTrace, 1); \
 	  nt->arg = (arg_);		       \
 	  nt->opcode = (op_);		       \
 	  nt->next = THREAD.trace;	       \
@@ -81,7 +83,7 @@ void* h_rvm_run__m(HAllocator *mm__, HRVMProg *prog, const uint8_t* input, size_
 	  THREAD.trace = nt;		       \
   } while(0)
 
-  ((HRVMTrace*)h_sarray_set(heads_n, 0, a_new(HRVMTrace, 1)))->opcode = SVM_NOP; // Initial thread
+  ((HRVMTrace*)h_sarray_set(heads_n, 0, a_new0(HRVMTrace, 1)))->opcode = SVM_NOP; // Initial thread
   
   size_t off = 0;
   int live_threads = 1; // May be redundant
@@ -257,7 +259,7 @@ HParseResult *run_trace(HAllocator *mm__, HRVMProg *orig_prog, HRVMTrace *trace,
       if (!svm_stack_ensure_cap(mm__, ctx, 1)) {
 	goto fail;
       }
-      tmp_res = a_new(HParsedToken, 1);
+      tmp_res = a_new0(HParsedToken, 1);
       tmp_res->token_type = TT_MARK;
       tmp_res->index = cur->input_pos;
       tmp_res->bit_offset = 0;
@@ -288,7 +290,7 @@ HParseResult *run_trace(HAllocator *mm__, HRVMProg *orig_prog, HRVMTrace *trace,
       break;
     case SVM_ACCEPT:
       assert(ctx->stack_count <= 1);
-      HParseResult *res = a_new(HParseResult, 1);
+      HParseResult *res = a_new0(HParseResult, 1);
       if (ctx->stack_count == 1) {
 	res->ast = ctx->stack[0];
       } else {
diff --git a/src/glue.c b/src/glue.c
index 37962e849283951972ed60094345bec62b57434f..da2f3af329232fc16c690441e679deefe7ed76e5 100644
--- a/src/glue.c
+++ b/src/glue.c
@@ -69,6 +69,7 @@ HParsedToken *h_act_flatten(const HParseResult *p, void* user_data) {
   res->seq = seq;
   res->index = p->ast->index;
   res->bit_offset = p->ast->bit_offset;
+  res->bit_length = p->bit_length;
   return res;
 }
 
diff --git a/src/parsers/bits.c b/src/parsers/bits.c
index 288e3e95a45a7709e942d9987cda37c7e55819b5..2b977a27401610a071f0bac42b7404f828351eed 100644
--- a/src/parsers/bits.c
+++ b/src/parsers/bits.c
@@ -14,6 +14,9 @@ static HParseResult* parse_bits(void* env, HParseState *state) {
     result->sint = h_read_bits(&state->input_stream, env_->length, true);
   else
     result->uint = h_read_bits(&state->input_stream, env_->length, false);
+  result->index = 0;
+  result->bit_length = 0;
+  result->bit_offset = 0;
   return make_result(state->arena, result);
 }
 
diff --git a/src/parsers/ch.c b/src/parsers/ch.c
index 3da1091a4b71505aebdc6ed5b396084d12b1fde4..c878f9d08659a1cb6ae39f95b06c522c1a5a185f 100644
--- a/src/parsers/ch.c
+++ b/src/parsers/ch.c
@@ -8,6 +8,9 @@ static HParseResult* parse_ch(void* env, HParseState *state) {
   if (c == r) {
     HParsedToken *tok = a_new(HParsedToken, 1);    
     tok->token_type = TT_UINT; tok->uint = r;
+    tok->index = 0;
+    tok->bit_length = 0;
+    tok->bit_offset = 0;
     return make_result(state->arena, tok);
   } else {
     return NULL;
diff --git a/src/parsers/charset.c b/src/parsers/charset.c
index a4b8c89c7daca326cf77ee9bf5c8ae4660884c56..01657386f68e9788e69635790df6efb600de4c94 100644
--- a/src/parsers/charset.c
+++ b/src/parsers/charset.c
@@ -10,6 +10,9 @@ static HParseResult* parse_charset(void *env, HParseState *state) {
   if (charset_isset(cs, in)) {
     HParsedToken *tok = a_new(HParsedToken, 1);
     tok->token_type = TT_UINT; tok->uint = in;
+    tok->index = 0;
+    tok->bit_length = 0;
+    tok->bit_offset = 0;
     return make_result(state->arena, tok);    
   } else
     return NULL;
diff --git a/src/parsers/end.c b/src/parsers/end.c
index 85499d9348cd1df6503428a55d7a2ab878d1ef63..35e4186d430d8b48fe5cd1e41552403d6f95e562 100644
--- a/src/parsers/end.c
+++ b/src/parsers/end.c
@@ -4,6 +4,8 @@ static HParseResult* parse_end(void *env, HParseState *state) {
   if (state->input_stream.index == state->input_stream.length) {
     HParseResult *ret = a_new(HParseResult, 1);
     ret->ast = NULL;
+    ret->bit_length = 0;
+    ret->arena = state->arena;
     return ret;
   } else {
     return NULL;
diff --git a/src/parsers/epsilon.c b/src/parsers/epsilon.c
index bb6e8beb31cca3ff09a565171b4e554e07f2ffad..be614489cecfec6f30e4c2bfdd18c323be894446 100644
--- a/src/parsers/epsilon.c
+++ b/src/parsers/epsilon.c
@@ -5,6 +5,7 @@ static HParseResult* parse_epsilon(void* env, HParseState* state) {
   HParseResult* res = a_new(HParseResult, 1);
   res->ast = NULL;
   res->arena = state->arena;
+  res->bit_length = 0;
   return res;
 }
 
diff --git a/src/parsers/ignore.c b/src/parsers/ignore.c
index c56802ac0885fc11429925f353a516d622b88a9d..7eda13d23eecfc771eb82d40db90c81387be146f 100644
--- a/src/parsers/ignore.c
+++ b/src/parsers/ignore.c
@@ -8,6 +8,7 @@ static HParseResult* parse_ignore(void* env, HParseState* state) {
   HParseResult *res = a_new(HParseResult, 1);
   res->ast = NULL;
   res->arena = state->arena;
+  res->bit_length = 0;
   return res;
 }
 
diff --git a/src/parsers/many.c b/src/parsers/many.c
index 77b9dd8be220d92eac36b18ddbcd2fe263945448..655dd1497667f44b3de6694a0109c6f58804167d 100644
--- a/src/parsers/many.c
+++ b/src/parsers/many.c
@@ -37,6 +37,9 @@ static HParseResult *parse_many(void* env, HParseState *state) {
   HParsedToken *res = a_new(HParsedToken, 1);
   res->token_type = TT_SEQUENCE;
   res->seq = seq;
+  res->index = 0;
+  res->bit_length = 0;
+  res->bit_offset = 0;
   return make_result(state->arena, res);
  err0:
   if (count >= env_->count) {
@@ -85,6 +88,7 @@ static HParsedToken *reshape_many(const HParseResult *p, void *user)
   res->seq = seq;
   res->index = p->ast->index;
   res->bit_offset = p->ast->bit_offset;
+  res->bit_length = p->bit_length;
   return res;
 }
 
diff --git a/src/parsers/optional.c b/src/parsers/optional.c
index 726606643056b103f9481cb882dadc19417dd607..6a2789e2d0a86a8c4e6b141825fd3abc075af5d0 100644
--- a/src/parsers/optional.c
+++ b/src/parsers/optional.c
@@ -9,6 +9,9 @@ static HParseResult* parse_optional(void* env, HParseState* state) {
   state->input_stream = bak;
   HParsedToken *ast = a_new(HParsedToken, 1);
   ast->token_type = TT_NONE;
+  ast->index = 0;
+  ast->bit_length = 0;
+  ast->bit_offset = 0;
   return make_result(state->arena, ast);
 }
 
diff --git a/src/parsers/parser_internal.h b/src/parsers/parser_internal.h
index 9a3b6de3898b42336a84bfe565448c27315e29bb..ebc5f4b32992d77cae4e6b512d17e3a39729e14f 100644
--- a/src/parsers/parser_internal.h
+++ b/src/parsers/parser_internal.h
@@ -10,12 +10,13 @@
 #include "../backends/regex.h"
 #include "../backends/contextfree.h"
 
-#define a_new_(arena, typ, count) ((typ*)h_arena_malloc((arena), sizeof(typ)*(count)))
+#define a_new_(arena, typ, count) ((typ*)h_arena_malloc_noinit((arena), sizeof(typ)*(count)))
 #define a_new(typ, count) a_new_(state->arena, typ, count)
-// we can create a_new0 if necessary. It would allocate some memory and immediately zero it out.
+#define a_new0_(arena, typ, count) ((typ*)h_arena_malloc((arena), sizeof(typ)*(count)))
+#define a_new0(typ, count) a_new0_(state->arena, typ, count)
 
 static inline HParseResult* make_result(HArena *arena, HParsedToken *tok) {
-  HParseResult *ret = h_arena_malloc(arena, sizeof(HParseResult));
+  HParseResult *ret = h_arena_malloc_noinit(arena, sizeof(HParseResult));
   ret->ast = tok;
   ret->arena = arena;
   ret->bit_length = 0; // This way it gets overridden in h_do_parse
diff --git a/src/parsers/permutation.c b/src/parsers/permutation.c
index ec256c4af1f76292847102d0a07eca5cb19e5bae..c40f99da2d52eea8dcbce93882d4aed7a0307360 100644
--- a/src/parsers/permutation.c
+++ b/src/parsers/permutation.c
@@ -89,6 +89,9 @@ static HParseResult *parse_permutation(void *env, HParseState *state)
     HParsedToken *tok = a_new(HParsedToken, 1);
     tok->token_type  = TT_SEQUENCE;
     tok->seq = seq;
+    tok->index = 0;
+    tok->bit_length = 0;
+    tok->bit_offset = 0;
     return make_result(state->arena, tok);
   } else {
     // no parse
diff --git a/src/parsers/seek.c b/src/parsers/seek.c
index 027098b59424a2f78c9b54a0683e66111c02863f..d5bc02840f0145dc3089e82c11068359932b454c 100644
--- a/src/parsers/seek.c
+++ b/src/parsers/seek.c
@@ -49,6 +49,9 @@ static HParseResult *parse_seek(void *env, HParseState *state)
   HParsedToken *tok = a_new(HParsedToken, 1);
   tok->token_type = TT_UINT;
   tok->uint = pos;
+  tok->index = 0;
+  tok->bit_length = 0;
+  tok->bit_offset = 0;
   return make_result(state->arena, tok);
 }
 
@@ -57,6 +60,9 @@ static HParseResult *parse_tell(void *env, HParseState *state)
   HParsedToken *tok = a_new(HParsedToken, 1);
   tok->token_type = TT_UINT;
   tok->uint = h_input_stream_pos(&state->input_stream);
+  tok->index = 0;
+  tok->bit_length = 0;
+  tok->bit_offset = 0;
   return make_result(state->arena, tok);
 }
 
diff --git a/src/parsers/sequence.c b/src/parsers/sequence.c
index 786ba62e43683f32ca0cc244bc0695cdb04a76fd..2e7b4bc7286ec0ac32af012126e4289226297be0 100644
--- a/src/parsers/sequence.c
+++ b/src/parsers/sequence.c
@@ -22,6 +22,9 @@ static HParseResult* parse_sequence(void *env, HParseState *state) {
   }
   HParsedToken *tok = a_new(HParsedToken, 1);
   tok->token_type = TT_SEQUENCE; tok->seq = seq;
+  tok->index = 0;
+  tok->bit_offset = 0;
+  tok->bit_length = 0;
   return make_result(state->arena, tok);
 }
 
@@ -60,6 +63,7 @@ static HParsedToken *reshape_sequence(const HParseResult *p, void* user_data) {
   res->seq = seq;
   res->index = p->ast->index;
   res->bit_offset = p->ast->bit_offset;
+  res->bit_length = p->bit_length;
 
   return res;
 }
diff --git a/src/parsers/token.c b/src/parsers/token.c
index 19029726ad11a52fa0eadf62b67a7b15cd2e4744..b589d58c60e39bb895395a2eedb48984a0b8669f 100644
--- a/src/parsers/token.c
+++ b/src/parsers/token.c
@@ -16,6 +16,9 @@ static HParseResult* parse_token(void *env, HParseState *state) {
   }
   HParsedToken *tok = a_new(HParsedToken, 1);
   tok->token_type = TT_BYTES; tok->bytes.token = t->str; tok->bytes.len = t->len;
+  tok->index = 0;
+  tok->bit_offset = 0;
+  tok->bit_length = 0;
   return make_result(state->arena, tok);
 }
 
diff --git a/src/t_parser.c b/src/t_parser.c
index cb67901ed9227787d5580079112c410df000dd94..2d933ef1d3a025fd15fa8a1e247dc8ced3ba63ea 100644
--- a/src/t_parser.c
+++ b/src/t_parser.c
@@ -205,12 +205,12 @@ HParsedToken* upcase(const HParseResult *p, void* user_data) {
   switch(p->ast->token_type) {
   case TT_SEQUENCE:
     {
-      HParsedToken *ret = a_new_(p->arena, HParsedToken, 1);
+      HParsedToken *ret = a_new0_(p->arena, HParsedToken, 1);
       HCountedArray *seq = h_carray_new_sized(p->arena, p->ast->seq->used);
       ret->token_type = TT_SEQUENCE;
       for (size_t i=0; i<p->ast->seq->used; ++i) {
 	if (TT_UINT == ((HParsedToken*)p->ast->seq->elements[i])->token_type) {
-	  HParsedToken *tmp = a_new_(p->arena, HParsedToken, 1);
+	  HParsedToken *tmp = a_new0_(p->arena, HParsedToken, 1);
 	  tmp->token_type = TT_UINT;
 	  tmp->uint = toupper(((HParsedToken*)p->ast->seq->elements[i])->uint);
 	  h_carray_append(seq, tmp);
@@ -223,7 +223,7 @@ HParsedToken* upcase(const HParseResult *p, void* user_data) {
     }
   case TT_UINT:
     {
-      HParsedToken *ret = a_new_(p->arena, HParsedToken, 1);
+      HParsedToken *ret = a_new0_(p->arena, HParsedToken, 1);
       ret->token_type = TT_UINT;
       ret->uint = toupper(p->ast->uint);
       return ret;
@@ -674,7 +674,7 @@ static void test_endianness(gconstpointer backend) {
 }
 
 HParsedToken* act_get(const HParseResult *p, void* user_data) {
-  HParsedToken *ret = a_new_(p->arena, HParsedToken, 1);
+  HParsedToken *ret = a_new0_(p->arena, HParsedToken, 1);
   ret->token_type = TT_UINT;
   ret->uint = 3 * (1 << p->ast->uint);
   return ret;