diff -urN autotrace-0.31.1.old/xstd.h autotrace-0.31.1/xstd.h
--- autotrace-0.31.1.old/xstd.h	2002-10-11 02:14:17.000000000 +0530
+++ autotrace-0.31.1/xstd.h	2021-04-30 15:22:25.853589944 +0530
@@ -20,6 +20,7 @@
 #define XMALLOC(new_mem, size)			\
 do						\
   {						\
+    assert(size);                              \
     new_mem = (at_address) malloc (size);	\
     assert(new_mem);				\
   } while (0)
@@ -28,6 +29,7 @@
 #define XCALLOC(new_mem, size)			\
 do						\
   {						\
+    assert(size);                              \
     new_mem = (at_address) calloc (size, 1);	\
     assert(new_mem);				\
   } while (0)
@@ -55,6 +57,7 @@
 #define XMALLOC(new_mem, size)					\
 do								\
   {								\
+    assert(size);                                              \
     (at_address&)(new_mem) = (at_address) malloc (size);	\
      assert(new_mem);						\
   } while (0) 
@@ -63,6 +66,7 @@
 #define XCALLOC(new_mem, sizex)					\
 do								\
   {								\
+    assert(size);                                              \
     (at_address&)(new_mem) = (void *) calloc (sizex, 1);	\
     assert(new_mem);						\
   } while (0)