diff --git a/src/network/core/address.cpp b/src/network/core/address.cpp
--- a/src/network/core/address.cpp
+++ b/src/network/core/address.cpp
@@ -143,7 +143,7 @@ bool NetworkAddress::IsFamily(int family
  * @note netmask without /n assumes all bits need to match.
  * @return true if this IP is within the netmask.
  */
-bool NetworkAddress::IsInNetmask(const char *netmask)
+bool NetworkAddress::IsInNetmask(const std::string &netmask)
 {
 	/* Resolve it if we didn't do it already */
 	if (!this->IsResolved()) this->GetAddress();
@@ -153,16 +153,15 @@ bool NetworkAddress::IsInNetmask(const c
 	NetworkAddress mask_address;
 
 	/* Check for CIDR separator */
-	const char *chr_cidr = strchr(netmask, '/');
-	if (chr_cidr != nullptr) {
-		int tmp_cidr = atoi(chr_cidr + 1);
+	auto cidr_separator_location = netmask.find('/');
+	if (cidr_separator_location != std::string::npos) {
+		int tmp_cidr = atoi(netmask.substr(cidr_separator_location + 1).c_str());
 
 		/* Invalid CIDR, treat as single host */
 		if (tmp_cidr > 0 && tmp_cidr < cidr) cidr = tmp_cidr;
 
 		/* Remove the / so that NetworkAddress works on the IP portion */
-		std::string ip_str(netmask, chr_cidr - netmask);
-		mask_address = NetworkAddress(ip_str.c_str(), 0, this->address.ss_family);
+		mask_address = NetworkAddress(netmask.substr(0, cidr_separator_location), 0, this->address.ss_family);
 	} else {
 		mask_address = NetworkAddress(netmask, 0, this->address.ss_family);
 	}