diff --git a/Libraries/LibC/stdlib.cpp b/Libraries/LibC/stdlib.cpp
index 2adcba1d44..b65455214b 100644
--- a/Libraries/LibC/stdlib.cpp
+++ b/Libraries/LibC/stdlib.cpp
@@ -760,7 +760,7 @@ void* bsearch(const void* key, const void* base, size_t nmemb, size_t size, int
         nmemb /= 2;
     }
 
-    return NULL;
+    return nullptr;
 }
 
 div_t div(int numerator, int denominator)
diff --git a/Libraries/LibC/sys/socket.h b/Libraries/LibC/sys/socket.h
index 298b863388..e39092c0d7 100644
--- a/Libraries/LibC/sys/socket.h
+++ b/Libraries/LibC/sys/socket.h
@@ -169,7 +169,7 @@ static inline struct cmsghdr* CMSG_NXTHDR(struct msghdr* msg, struct cmsghdr* cm
     struct cmsghdr* next = (struct cmsghdr*)((char*)cmsg + CMSG_ALIGN(cmsg->cmsg_len));
     unsigned offset = (char*)next - (char*)msg->msg_control;
     if (msg->msg_controllen < offset + sizeof(struct cmsghdr))
-        return NULL;
+        return nullptr;
     return next;
 }
 
diff --git a/Libraries/LibC/syslog.h b/Libraries/LibC/syslog.h
index 77f3e419eb..1a396e67f6 100644
--- a/Libraries/LibC/syslog.h
+++ b/Libraries/LibC/syslog.h
@@ -132,7 +132,7 @@ CODE prioritynames[] = {
     { "none",    INTERNAL_NOPRI },
     { "notice",  LOG_NOTICE },
     { "warning", LOG_WARNING },
-    { NULL, -1 },
+    { nullptr, -1 },
 };
 
 CODE facilitynames[] = {
@@ -158,7 +158,7 @@ CODE facilitynames[] = {
     { "syslog",   LOG_SYSLOG },
     { "user",     LOG_USER },
     { "uucp",     LOG_UUCP },
-    { NULL, -1 },
+    { nullptr, -1 },
 };
 #endif
 
diff --git a/Libraries/LibGfx/PNGLoader.cpp b/Libraries/LibGfx/PNGLoader.cpp
index 0dae43e948..320787e5f7 100644
--- a/Libraries/LibGfx/PNGLoader.cpp
+++ b/Libraries/LibGfx/PNGLoader.cpp
@@ -745,7 +745,7 @@ static bool decode_png_bitmap(PNGLoadingContext& context)
 
     unsigned long srclen = context.compressed_data.size() - 6;
     unsigned long destlen = 0;
-    int ret = puff(NULL, &destlen, context.compressed_data.data() + 2, &srclen);
+    int ret = puff(nullptr, &destlen, context.compressed_data.data() + 2, &srclen);
     if (ret != 0) {
         context.state = PNGLoadingContext::State::Error;
         return false;
diff --git a/Shell/main.cpp b/Shell/main.cpp
index cf1dfddf1b..4ab4805a5b 100644
--- a/Shell/main.cpp
+++ b/Shell/main.cpp
@@ -72,7 +72,7 @@ int main(int argc, char** argv)
     sigemptyset(&blocked);
     sigaddset(&blocked, SIGTTOU);
     sigaddset(&blocked, SIGTTIN);
-    pthread_sigmask(SIG_BLOCK, &blocked, NULL);
+    pthread_sigmask(SIG_BLOCK, &blocked, nullptr);
 #endif
 #ifdef __serenity__
     if (pledge("stdio rpath wpath cpath proc exec tty accept sigaction unix fattr", nullptr) < 0) {
diff --git a/Userland/nc.cpp b/Userland/nc.cpp
index 13fee77f10..1f726488f0 100644
--- a/Userland/nc.cpp
+++ b/Userland/nc.cpp
@@ -175,7 +175,7 @@ int main(int argc, char** argv)
             highest_fd = max(highest_fd, fd);
         }
 
-        int ready = select(highest_fd + 1, &readfds, &writefds, &exceptfds, NULL);
+        int ready = select(highest_fd + 1, &readfds, &writefds, &exceptfds, nullptr);
         if (ready == -1) {
             if (errno == EINTR)
                 continue;
diff --git a/Userland/wc.cpp b/Userland/wc.cpp
index 497e5e937d..708df9c96b 100644
--- a/Userland/wc.cpp
+++ b/Userland/wc.cpp
@@ -65,7 +65,7 @@ static Count get_count(const String& file_name)
         file_pointer = stdin;
     } else {
         count.name = file_name;
-        if ((file_pointer = fopen(file_name.characters(), "r")) == NULL) {
+        if ((file_pointer = fopen(file_name.characters(), "r")) == nullptr) {
             fprintf(stderr, "wc: unable to open %s\n", file_name.characters());
             count.exists = false;
             return count;