diff --git a/internal/getonescriptspan.cc b/internal/getonescriptspan.cc
index 3d93a40..73aa033 100644
--- a/internal/getonescriptspan.cc
+++ b/internal/getonescriptspan.cc
@@ -328,6 +328,7 @@ int hex_digit_to_int(char c) {
   if (('0' <= c) && (c <= '9')) {return c - '0';}
   if (('a' <= c) && (c <= 'f')) {return c - 'a' + 10;}
   if (('A' <= c) && (c <= 'F')) {return c - 'A' + 10;}
+  return 0;
 }
 
 static int32 strto32_base10(const char* nptr, const char* limit,