diff --git a/C/iopreds.c b/C/iopreds.c
index 043cea1b1..851bd9d30 100644
--- a/C/iopreds.c
+++ b/C/iopreds.c
@@ -3073,6 +3073,11 @@ static Int
 	  if (!Yap_ExpandPreAllocCodeSpace(0, NULL)) {
 	    return FALSE;
 	  }
+	} else if (Yap_Error_TYPE == OUT_OF_HEAP_ERROR) {
+	  Yap_Error_TYPE = YAP_NO_ERROR;
+	  if (!Yap_growheap(FALSE, 0, NULL)) {
+	    return FALSE;
+	  }
 	} else if (Yap_Error_TYPE == OUT_OF_STACK_ERROR) {
 	  Yap_Error_TYPE = YAP_NO_ERROR;
 	  if (!Yap_gc(nargs, ENV, CP)) {
@@ -4142,7 +4147,7 @@ format(volatile Term otail, volatile Term oargs, int sno)
 	    if (IsIntegerTerm(t)) {
 	      Int il = IntegerOfTerm(t);
 #if HAVE_SNPRINTF
-	      snprintf(tmp1, 256, "%ld", il);
+	      snprintf(tmp1, 256, "%ld", (long int)il);
 #else
 	      sprintf(tmp1, "%ld", (long int)il);
 #endif
diff --git a/C/scanner.c b/C/scanner.c
index aa4d80259..8782d67f8 100644
--- a/C/scanner.c
+++ b/C/scanner.c
@@ -752,6 +752,7 @@ Yap_tokenizer(int inp_stream)
 	  /* huge atom or variable, we are in trouble */
 	  Yap_ErrorMessage = "Code Space Overflow due to huge atom";
 	  Yap_Error_TYPE = OUT_OF_AUXSPACE_ERROR;	  
+	  Yap_ReleasePreAllocCodeSpace((CODEADDR)TokImage);
 	  if (p)
 	    p->Tok = Ord(kind = eot_tok);
 	  /* serious error now */
@@ -764,6 +765,7 @@ Yap_tokenizer(int inp_stream)
 	/* don't do this in iso */
 	Atom ae = Yap_LookupAtom(TokImage);
 	if (ae == NIL) {
+	  Yap_Error_TYPE = OUT_OF_HEAP_ERROR;	  
 	  Yap_ErrorMessage = "Code Space Overflow";
 	  if (p)
 	    t->Tok = Ord(kind = eot_tok);
diff --git a/changes-5.1.html b/changes-5.1.html
index 727b51020..f8e42c5d0 100644
--- a/changes-5.1.html
+++ b/changes-5.1.html
@@ -16,6 +16,8 @@
 
 <h2>Yap-5.1.0:</h2>
 <ul>
+<li> FIXED: handle heap overflow from huge atoms in
+Yap_LookupAtom/scanner (Nuno Fonseca).</li>
 <li> FIXED: bignum was using int where should be long int (Roberto Bagnara).</li>
 <li> NEW: x86_64 should have registers, right? First cut at using them.</li>
 <li> FIXED: call_n would break under 64 bits, an int problem.</li>