diff --git a/libraries/AP_Common/Bitmask.cpp b/libraries/AP_Common/Bitmask.cpp
index 9d0806cd40..9af9a0c3ca 100644
--- a/libraries/AP_Common/Bitmask.cpp
+++ b/libraries/AP_Common/Bitmask.cpp
@@ -18,10 +18,7 @@ Bitmask &Bitmask::operator=(const Bitmask&other)
         }
         numbits = other.numbits;
     }
-    if (other.numwords > 20) {
-        abort();
-    }
-    memcpy(bits, other.bits, 4*other.numwords);
+    memcpy(bits, other.bits, sizeof(bits[0])*other.numwords);
 
     return *this;
 }