gistfile1.txt

diff --git i/usdt.c w/usdt.c
index 7a25621..078f437 100644
--- i/usdt.c
+++ w/usdt.c
@@ -148,7 +148,7 @@ usdt_provider_enable(usdt_provider_t *provider)
                 return (-1);
         }
 
-        if ((usdt_strtab_add(&strtab, provider->name)) < 0) {
+        if ((usdt_strtab_add(&strtab, provider->name)) == 0) {
                 usdt_error(provider, USDT_ERROR_MALLOC);
                 return (-1);
         }
diff --git i/usdt_dof.c w/usdt_dof.c
index a844533..1cd6bb0 100644
--- i/usdt_dof.c
+++ w/usdt_dof.c
@@ -112,11 +112,11 @@ usdt_strtab_add(usdt_strtab_t *strtab, const char *string)
         strtab->strindex += (length + 1);
 
         if ((strtab->data = realloc(strtab->data, strtab->strindex)) == NULL)
-                return (-1);
+                return (0); /* note error return; new string index is never 0 */
 
         memcpy((char *) (strtab->data + index), (char *)string, length + 1);
         strtab->size = index + length + 1;
 
-        return index;
+        return(index);
 }