diff --git a/DMRAccessControl.cpp b/DMRAccessControl.cpp
index 75ec36c..9c166d2 100644
--- a/DMRAccessControl.cpp
+++ b/DMRAccessControl.cpp
@@ -61,7 +61,7 @@ bool CDMRAccessControl::validateSrcId(unsigned int id)
 		return false;
 
 	unsigned int prefix = id / 10000U;
-	if (prefix == 0U || prefix > 999U)
+	if (prefix == 0U || prefix > 9999U)
 		return false;
 
 	if (!m_prefixes.empty()) {