diff --git a/tests/cts/net/jni/NativeMultinetworkJni.c b/tests/cts/net/jni/NativeMultinetworkJni.c
index 6990efa452..91565043ec 100644
--- a/tests/cts/net/jni/NativeMultinetworkJni.c
+++ b/tests/cts/net/jni/NativeMultinetworkJni.c
@@ -88,7 +88,9 @@ JNIEXPORT jint Java_android_net_cts_MultinetworkApiTest_runSetsocknetwork(
     return rval == 0 ? 0 : -saved_errno;
 }
 
-static const int kSockaddrStrLen = INET6_ADDRSTRLEN + strlen("[]:65535");
+// Use sizeof("x") - 1 because we need a compile-time constant, and strlen("x")
+// isn't guaranteed to fold to a constant.
+static const int kSockaddrStrLen = INET6_ADDRSTRLEN + sizeof("[]:65535") - 1;
 
 void sockaddr_ntop(const struct sockaddr *sa, socklen_t salen, char *dst, const size_t size) {
     char addrstr[INET6_ADDRSTRLEN];