diff --git a/libs/libc/stdlib/lib_checkbase.c b/libs/libc/stdlib/lib_checkbase.c
index 0cd0546f3a7..c70c436cf26 100644
--- a/libs/libc/stdlib/lib_checkbase.c
+++ b/libs/libc/stdlib/lib_checkbase.c
@@ -69,18 +69,21 @@ int lib_checkbase(int base, FAR const char **pptr)
 
       if (*ptr == '0')
         {
-          /* Assume octal */
-
-          base = 8;
-          ptr++;
-
-          /* Check for hexadecimal */
-
-          if ((*ptr == 'X' || *ptr == 'x') &&
-              lib_isbasedigit(ptr[1], 16, NULL))
+          if (ptr[1] != '\0')
             {
-              base = 16;
+              /* Assume octal */
+
+              base = 8;
               ptr++;
+
+              /* Check for hexadecimal */
+
+              if ((*ptr == 'X' || *ptr == 'x') &&
+                  lib_isbasedigit(ptr[1], 16, NULL))
+                {
+                  base = 16;
+                  ptr++;
+                }
             }
         }
     }