diff --git a/src/encString.cpp b/src/encString.cpp
index 3f629c7..68020e9 100644
--- a/src/encString.cpp
+++ b/src/encString.cpp
@@ -7,6 +7,8 @@ bool isBase64(const char *p)
 {
     char c;
 
+    if (!p)
+        return false;
     if (strlen(p) % 4 != 0)
         return false;
     do {