diff --git a/src/ccmain/paragraphs.cpp b/src/ccmain/paragraphs.cpp
index a204c6c8cd..43d3f9a3e8 100644
--- a/src/ccmain/paragraphs.cpp
+++ b/src/ccmain/paragraphs.cpp
@@ -324,7 +324,7 @@ int UnicodeSpanSkipper::SkipRomans(int pos) {
   const char *kRomans = "ivxlmdIVXLMD";
   while (pos < wordlen_) {
     int ch = UnicodeFor(u_, word_, pos);
-    if (ch >= 0xF0 || strchr(kRomans, ch) == 0) break;
+    if (ch >= 0xF0 || strchr(kRomans, ch) == nullptr) break;
     pos++;
   }
   return pos;
diff --git a/src/ccstruct/matrix.h b/src/ccstruct/matrix.h
index 209589d67a..9efde3c300 100644
--- a/src/ccstruct/matrix.h
+++ b/src/ccstruct/matrix.h
@@ -44,7 +44,7 @@
 class BLOB_CHOICE_LIST;
 class UNICHARSET;
 
-#define NOT_CLASSIFIED static_cast<BLOB_CHOICE_LIST*>(0)
+#define NOT_CLASSIFIED static_cast<BLOB_CHOICE_LIST*>(nullptr)
 
 // A generic class to hold a 2-D matrix with entries of type T, but can also
 // act as a base class for other implementations, such as a triangular or
diff --git a/src/ccutil/genericvector.h b/src/ccutil/genericvector.h
index d15add451a..64c5c9e481 100644
--- a/src/ccutil/genericvector.h
+++ b/src/ccutil/genericvector.h
@@ -657,9 +657,9 @@ template <typename T>
 void GenericVector<T>::init(int size) {
   size_used_ = 0;
   size_reserved_ = 0;
-  data_ = 0;
-  clear_cb_ = 0;
-  compare_cb_ = 0;
+  data_ = nullptr;
+  clear_cb_ = nullptr;
+  compare_cb_ = nullptr;
   reserve(size);
 }
 
diff --git a/src/ccutil/unicity_table.h b/src/ccutil/unicity_table.h
index 0c0c5d11e0..3aef73fcf0 100644
--- a/src/ccutil/unicity_table.h
+++ b/src/ccutil/unicity_table.h
@@ -106,7 +106,7 @@ class UnicityTableEqEq : public UnicityTable<T> {
 
 template <typename T>
 UnicityTable<T>::UnicityTable() :
-  compare_cb_(0) {
+  compare_cb_(nullptr) {
 }
 
 
diff --git a/src/cutil/oldlist.h b/src/cutil/oldlist.h
index e57f7c0fc4..13f188445b 100644
--- a/src/cutil/oldlist.h
+++ b/src/cutil/oldlist.h
@@ -123,7 +123,9 @@
 /*----------------------------------------------------------------------
                   T y p e s
 ----------------------------------------------------------------------*/
-#define NIL_LIST  (LIST) 0
+
+#define NIL_LIST  ((LIST)nullptr)
+
 struct list_rec
 {
   struct list_rec *node;
diff --git a/src/textord/fpchop.cpp b/src/textord/fpchop.cpp
index ac9c7c2544..eeb664bcc2 100644
--- a/src/textord/fpchop.cpp
+++ b/src/textord/fpchop.cpp
@@ -656,8 +656,8 @@ void close_chopped_cfragments(                             //chop the outline
     bottom_frag = frag_it.extract();
     frag_it.forward();
     top_frag = frag_it.data();  // look at next
-    if ((bottom_frag->steps == 0 && top_frag->steps == 0)
-    || (bottom_frag->steps != 0 && top_frag->steps != 0)) {
+    if ((bottom_frag->steps == nullptr && top_frag->steps == nullptr)
+    || (bottom_frag->steps != nullptr && top_frag->steps != nullptr)) {
       if (frag_it.data_relative(1)->ycoord == top_frag->ycoord)
         frag_it.forward();
     }
@@ -703,7 +703,7 @@ C_OUTLINE *join_chopped_fragments(                         //join pieces
   C_OUTLINE *outline;            //closed loop
 
   if (bottom->other_end == top) {
-    if (bottom->steps == 0)
+    if (bottom->steps == nullptr)
       outline = top->close ();   //turn to outline
     else
       outline = bottom->close ();
@@ -711,12 +711,12 @@ C_OUTLINE *join_chopped_fragments(                         //join pieces
     delete bottom;
     return outline;
   }
-  if (bottom->steps == 0) {
-    ASSERT_HOST (top->steps != 0);
+  if (bottom->steps == nullptr) {
+    ASSERT_HOST (top->steps != nullptr);
     join_segments (bottom->other_end, top);
   }
   else {
-    ASSERT_HOST (top->steps == 0);
+    ASSERT_HOST (top->steps == nullptr);
     join_segments (top->other_end, bottom);
   }
   top->other_end->other_end = bottom->other_end;
diff --git a/src/training/pango_font_info.cpp b/src/training/pango_font_info.cpp
index 20a361a392..7725dcc48a 100644
--- a/src/training/pango_font_info.cpp
+++ b/src/training/pango_font_info.cpp
@@ -554,7 +554,7 @@ const std::vector<std::string>& FontUtils::ListAvailableFonts() {
   }
 #endif
 
-  PangoFontFamily** families = 0;
+  PangoFontFamily** families = nullptr;
   int n_families = 0;
   ListFontFamilies(&families, &n_families);
   for (int i = 0; i < n_families; ++i) {
diff --git a/src/viewer/scrollview.cpp b/src/viewer/scrollview.cpp
index 64f0aa8653..b0c0e67346 100644
--- a/src/viewer/scrollview.cpp
+++ b/src/viewer/scrollview.cpp
@@ -144,7 +144,7 @@ void* ScrollView::MessageReceiver(void* a) {
                                                         cur->type);
       std::pair<ScrollView*, SVEventType> awaiting_list_any(cur->window,
                                                             SVET_ANY);
-      std::pair<ScrollView*, SVEventType> awaiting_list_any_window((ScrollView*)0,
+      std::pair<ScrollView*, SVEventType> awaiting_list_any_window((ScrollView*)nullptr,
                                                             SVET_ANY);
       waiting_for_events_mu->Lock();
       if (waiting_for_events.count(awaiting_list) > 0) {
@@ -444,7 +444,7 @@ SVEvent* ScrollView::AwaitEvent(SVEventType type) {
   SVSemaphore* sem = new SVSemaphore();
   std::pair<ScrollView*, SVEventType> ea(this, type);
   waiting_for_events_mu->Lock();
-  waiting_for_events[ea] = std::pair<SVSemaphore*, SVEvent*> (sem, (SVEvent*)0);
+  waiting_for_events[ea] = std::pair<SVSemaphore*, SVEvent*> (sem, (SVEvent*)nullptr);
   waiting_for_events_mu->Unlock();
   // Wait on it, but first flush.
   stream_->Flush();
@@ -463,9 +463,9 @@ SVEvent* ScrollView::AwaitEvent(SVEventType type) {
 SVEvent* ScrollView::AwaitEventAnyWindow() {
   // Initialize the waiting semaphore.
   SVSemaphore* sem = new SVSemaphore();
-  std::pair<ScrollView*, SVEventType> ea((ScrollView*)0, SVET_ANY);
+  std::pair<ScrollView*, SVEventType> ea((ScrollView*)nullptr, SVET_ANY);
   waiting_for_events_mu->Lock();
-  waiting_for_events[ea] = std::pair<SVSemaphore*, SVEvent*> (sem, (SVEvent*)0);
+  waiting_for_events[ea] = std::pair<SVSemaphore*, SVEvent*> (sem, (SVEvent*)nullptr);
   waiting_for_events_mu->Unlock();
   // Wait on it.
   stream_->Flush();