2 files changed, 10 insertions, 3 deletions

diff --git a/ptr.c b/ptr.c
index 2c63c3e..be3a4ae 100644
--- a/ptr.c
+++ b/ptr.c
@@ -37,6 +37,7 @@ ptr ptrnew __P1 (int,max)
     else if (max < 0 || max + sizeofptr < max) /* overflow! */
 	error = NO_MEM_ERROR;
     else if ((p = (ptr)malloc(max + sizeofptr))) {
+	p->signature = PTR_SIG;
 	p->max = max;
 	ptrdata(p)[p->len = 0] = '\0';
     } else
@@ -81,10 +82,12 @@ ptr ptrdup __P1 (ptr,src)
 }
 
 /* delete (free) a ptr */
-void ptrdel __P1 (ptr,p)
+void _ptrdel __P1 (ptr,p)
 {
-    if (p)
+    if (p && p->signature == PTR_SIG)
 	free((void *)p);
+    //else
+	//fprintf( stderr, "Tried to free non ptr @%x\n", p );
 }
 
 /* clear a ptr */
diff --git a/ptr.h b/ptr.h
index 06a0271..4f1654a 100644
--- a/ptr.h
+++ b/ptr.h
@@ -9,6 +9,7 @@
 typedef struct s_ptr {
     int len;
     int max;
+    int signature;
 } _ptr;
 
 typedef _ptr * ptr;
@@ -24,7 +25,10 @@ typedef _ptr * ptr;
 ptr   ptrnew    __P ((int max));
 ptr   ptrdup2   __P ((ptr src, int newmax));
 ptr   ptrdup    __P ((ptr src));
-void  ptrdel    __P ((ptr p));
+
+#define PTR_SIG 91887
+#define ptrdel(x) _ptrdel(x);x=(ptr)0;
+void  _ptrdel    __P ((ptr p));
 
 void  ptrzero   __P ((ptr p));
 void  ptrshrink __P ((ptr p, int len));