diff --git a/Source/DOH/string.c b/Source/DOH/string.c
index 1aede9e08..55882f83b 100644
--- a/Source/DOH/string.c
+++ b/Source/DOH/string.c
@@ -1037,7 +1037,7 @@ int DohStrncmp(const DOHString_or_char *s1, const DOHString_or_char *s2, int n)
 char *DohStrstr(const DOHString_or_char *s1, const DOHString_or_char *s2) {
   char* p1 = Char(s1);
   char* p2 = Char(s2);
-  return p2 == 0 || *p2 == '\0' ? p1 : strstr(p1,p2);
+  return p1 == 0 || p2 == 0 || *p2 == '\0' ? p1 : strstr(p1,p2);
 }
 
 char *DohStrchr(const DOHString_or_char *s1, int ch) {