diff --git a/lib/err.c b/lib/err.c
index 3c71df1..9f6e05d 100644
--- a/lib/err.c
+++ b/lib/err.c
@@ -27,6 +27,7 @@
 #include "hcl-prv.h"
 
 #if defined(HCL_ENABLE_LIBUNWIND)
+#	define UNW_LOCAL_ONLY
 #	include <libunwind.h>
 #endif
 
@@ -484,28 +485,27 @@ static void backtrace_stack_frames (hcl_t* hcl)
 {
 	unw_cursor_t cursor;
 	unw_context_t context;
+	int n;
 
 	unw_getcontext(&context);
 	unw_init_local(&cursor, &context);
 
-	int n=0;
-	while (unw_step(&cursor)) 
+	for (n = 0; unw_step(&cursor) > 0; n++) 
 	{
 		unw_word_t ip, sp, off;
+		char symbol[256];
 
 		unw_get_reg (&cursor, UNW_REG_IP, &ip);
 		unw_get_reg (&cursor, UNW_REG_SP, &sp);
 
-		char symbol[256];
-
-		if (!unw_get_proc_name(&cursor, symbol, HCL_COUNTOF(symbol), &off)) 
+		if (unw_get_proc_name(&cursor, symbol, HCL_COUNTOF(symbol), &off)) 
 		{
-			hcl_copy_bcstr (symbol, "<unknown>");
+			hcl_copy_bcstr (symbol, HCL_COUNTOF(symbol), "<unknown>");
 		}
 
 		hcl_logbfmt (hcl, HCL_LOG_UNTYPED | HCL_LOG_DEBUG, 
-			"#%-2d 0x%016p p=0x%016p %s + 0x%zu\n", 
-			++n, (void*)ip, (void*)sp, symbol, (hcl_oow_t)off);
+			"#%02d ip=0x%*p sp=0x%*p %s+0x%zu\n", 
+			n, HCL_SIZEOF(void*) * 2, (void*)ip, HCL_SIZEOF(void*) * 2, (void*)sp, symbol, (hcl_oow_t)off);
 	}
 }
 #elif defined(HAVE_BACKTRACE)