diff --git a/libraries/MySensors/MySensor.cpp b/libraries/MySensors/MySensor.cpp
index 6c3a348..8409e5d 100644
--- a/libraries/MySensors/MySensor.cpp
+++ b/libraries/MySensors/MySensor.cpp
@@ -24,9 +24,9 @@
 
 #ifdef MY_SIGNING_FEATURE
 // Macros for manipulating signing requirement table
-#define DO_SIGN(node) (node == 0 ? (~doSign[0]&1) : (~doSign[node>>4]&(node%16)))
-#define SET_SIGN(node) (node == 0 ? (doSign[0]&=~1) : (doSign[node>>4]&=~(node%16)))
-#define CLEAR_SIGN(node) (node == 0 ? (doSign[0]|=1) : (doSign[node>>4]|=(node%16)))
+#define DO_SIGN(node) (~_doSign[node>>3]&(1<<(node%8)))
+#define SET_SIGN(node) (_doSign[node>>3]&=~(1<<(node%8)))
+#define CLEAR_SIGN(node) (_doSign[node>>3]|=(1<<(node%8)))
 #endif
 
 // Inline function and macros
diff --git a/libraries/MySensors/MySensor.h b/libraries/MySensors/MySensor.h
index 18f4cb7..ba6edc3 100644
--- a/libraries/MySensors/MySensor.h
+++ b/libraries/MySensors/MySensor.h
@@ -366,7 +366,7 @@ class MySensor
 
 	MyTransport& radio;
 #ifdef MY_SIGNING_FEATURE
-	uint16_t doSign[16]; // Bitfield indicating which sensors require signed communication
+	uint8_t doSign[32]; // Bitfield indicating which sensors require signed communication
 	MyMessage msgSign;  // Buffer for message to sign.
 	MySigning& signer;
 #endif