diff --git a/src/core/ngx_string.c b/src/core/ngx_string.c
index fd115cc..1e6ee64 100644
--- a/src/core/ngx_string.c
+++ b/src/core/ngx_string.c
@@ -88,12 +88,12 @@
         }
 
         if (ch >= 'A' && ch <= 'F') {
-            value = value * 16 + (*line - 'A');
+            value = value * 16 + (ch - 'A' + 10);
             continue;
         }
 
         if (ch >= 'a' && ch <= 'f') {
-            value = value * 16 + (*line - 'a');
+            value = value * 16 + (ch - 'a' + 10);
             continue;
         }