diff --git a/src/avian/classpath-common.h b/src/avian/classpath-common.h
index b877ae2425..9f625cbd3a 100644
--- a/src/avian/classpath-common.h
+++ b/src/avian/classpath-common.h
@@ -594,9 +594,13 @@ object invoke(Thread* t, GcMethod* method, object instance, object args)
       object arg = objectArrayBody(t, args, i++);
       if ((arg == 0 and (not objectType))
           or (arg and (not instanceOf(t, type, arg)))) {
-        // fprintf(stderr, "%s is not a %s\n", arg ? &byteArrayBody(t,
-        // className(t, objectClass(t, arg)), 0) : reinterpret_cast<const
-        // int8_t*>("<null>"), &byteArrayBody(t, className(t, type), 0));
+        if (false) {
+          fprintf(stderr,
+                  "%s is not a %s\n",
+                  arg ? objectClass(t, arg)->name()->body().begin()
+                      : reinterpret_cast<const int8_t*>("<null>"),
+                  type->name()->body().begin());
+        }
 
         throwNew(t, GcIllegalArgumentException::Type);
       }
@@ -661,12 +665,17 @@ void intercept(Thread* t,
   } else {
     // If we can't find the method, just ignore it, since ProGuard may
     // have stripped it out as unused.  Otherwise, the code below can
-    // be uncommented for debugging purposes.
+    // be enabled for debugging purposes.
 
-    // fprintf(stderr, "unable to find %s%s in %s\n",
-    //         name, spec, &byteArrayBody(t, c->name(), 0));
+    if (false) {
+      fprintf(stderr,
+              "unable to find %s%s in %s\n",
+              name,
+              spec,
+              c->name()->body().begin());
 
-    // abort(t);
+      abort(t);
+    }
   }
 }
 
diff --git a/src/codegen/compiler.cpp b/src/codegen/compiler.cpp
index edf2e50218..3a72d36176 100644
--- a/src/codegen/compiler.cpp
+++ b/src/codegen/compiler.cpp
@@ -1354,11 +1354,14 @@ unsigned frameFootprint(Context* c, Stack* s)
 
 void visit(Context* c, Link* link)
 {
-  //   fprintf(stderr, "visit link from %d to %d fork %p junction %p\n",
-  //           link->predecessor->logicalInstruction->index,
-  //           link->successor->logicalInstruction->index,
-  //           link->forkState,
-  //           link->junctionState);
+  if (false) {
+    fprintf(stderr,
+            "visit link from %d to %d fork %p junction %p\n",
+            link->predecessor->logicalInstruction->index,
+            link->successor->logicalInstruction->index,
+            link->forkState,
+            link->junctionState);
+  }
 
   ForkState* forkState = link->forkState;
   if (forkState) {
@@ -1366,8 +1369,9 @@ void visit(Context* c, Link* link)
       ForkElement* p = forkState->elements + i;
       Value* v = p->value;
       v->reads = p->read->nextTarget();
-      //       fprintf(stderr, "next read %p for %p from %p\n", v->reads, v,
-      //       p->read);
+      if (false) {
+        fprintf(stderr, "next read %p for %p from %p\n", v->reads, v, p->read);
+      }
       if (not live(c, v)) {
         v->clearSites(c);
       }
@@ -1865,9 +1869,16 @@ void restore(Context* c, Event* e, Snapshot* snapshots)
       }
     }
 
-    // char buffer[256]; sitesToString(c, s->sites, buffer, 256);
-    // fprintf(stderr, "restore %p buddy %p sites %s live %p\n",
-    //         s->value, s->value->buddy, buffer, live(c, s->value));
+    if (false) {
+      char buffer[256];
+      sitesToString(c, s->sites, buffer, 256);
+      fprintf(stderr,
+              "restore %p buddy %p sites %s live %p\n",
+              s->value,
+              s->value->buddy,
+              buffer,
+              live(c, s->value));
+    }
   }
 }
 
diff --git a/src/codegen/compiler/event.cpp b/src/codegen/compiler/event.cpp
index b4433da9cf..5bd721815a 100644
--- a/src/codegen/compiler/event.cpp
+++ b/src/codegen/compiler/event.cpp
@@ -148,9 +148,9 @@ void Event::addRead(Context* c, Value* v, Read* r)
   }
 
   if (v->lastRead) {
-    //     if (DebugReads) {
-    //       fprintf(stderr, "append %p to %p for %p\n", r, v->lastRead, v);
-    //     }
+    if (DebugReads) {
+      fprintf(stderr, "append %p to %p for %p\n", r, v->lastRead, v);
+    }
 
     v->lastRead->append(c, r);
   } else {
@@ -298,9 +298,9 @@ Value* slicePushWord(Context* c,
   assertT(c, slice.count < slice.capacity);
   slice.push(v);
 
-  // if (DebugFrame) {
-  //   fprintf(stderr, "push %p\n", v);
-  // }
+  if (false) {
+    fprintf(stderr, "push %p\n", v);
+  }
 
   if (v) {
     v->home = frameIndex(c, index + stackBase + c->localFootprint);
@@ -1102,13 +1102,19 @@ class CombineEvent : public Event {
         c,
         firstValue->source->type(c) == firstValue->nextWord->source->type(c));
 
-    // if (secondValue->source->type(c) !=
-    // secondValue->nextWord->source->type(c)) {
-    //   fprintf(stderr, "%p %p %d : %p %p %d\n",
-    //           secondValue, secondValue->source, secondValue->source->type(c),
-    //           secondValue->nextWord, secondValue->nextWord->source,
-    //           secondValue->nextWord->source->type(c));
-    // }
+    if (false) {
+      if (secondValue->source->type(c)
+          != secondValue->nextWord->source->type(c)) {
+        fprintf(stderr,
+                "%p %p %d : %p %p %d\n",
+                secondValue,
+                secondValue->source,
+                secondValue->source->type(c),
+                secondValue->nextWord,
+                secondValue->nextWord->source,
+                secondValue->nextWord->source->type(c));
+      }
+    }
 
     assertT(
         c,
@@ -1149,10 +1155,16 @@ class CombineEvent : public Event {
                                   resultHighMask)
                       : low);
 
-    //     fprintf(stderr, "combine %p:%p and %p:%p into %p:%p\n",
-    //             firstValue, firstValue->nextWord,
-    //             secondValue, secondValue->nextWord,
-    //             resultValue, resultValue->nextWord);
+    if (false) {
+      fprintf(stderr,
+              "combine %p:%p and %p:%p into %p:%p\n",
+              firstValue,
+              firstValue->nextWord,
+              secondValue,
+              secondValue->nextWord,
+              resultValue,
+              resultValue->nextWord);
+    }
 
     apply(c,
           op,
diff --git a/src/codegen/compiler/read.cpp b/src/codegen/compiler/read.cpp
index 3eb6564f37..0c7d09fd76 100644
--- a/src/codegen/compiler/read.cpp
+++ b/src/codegen/compiler/read.cpp
@@ -123,7 +123,9 @@ void MultiRead::append(Context* c, Read* r)
   }
   lastRead = cell;
 
-  //     fprintf(stderr, "append %p to %p for %p\n", r, lastTarget, this);
+  if (false) {
+    fprintf(stderr, "append %p to %p for %p\n", r, lastTarget, this);
+  }
 
   lastTarget->item = r;
 }
@@ -137,7 +139,9 @@ void MultiRead::allocateTarget(Context* c)
 {
   List<Read*>* cell = cons<Read*>(c, 0, 0);
 
-  //     fprintf(stderr, "allocate target for %p: %p\n", this, cell);
+  if (false) {
+    fprintf(stderr, "allocate target for %p: %p\n", this, cell);
+  }
 
   if (lastTarget) {
     lastTarget->next = cell;
@@ -149,7 +153,9 @@ void MultiRead::allocateTarget(Context* c)
 
 Read* MultiRead::nextTarget()
 {
-  //     fprintf(stderr, "next target for %p: %p\n", this, firstTarget);
+  if (false) {
+    fprintf(stderr, "next target for %p: %p\n", this, firstTarget);
+  }
 
   Read* r = firstTarget->item;
   firstTarget = firstTarget->next;
diff --git a/src/codegen/target/arm/assembler.cpp b/src/codegen/target/arm/assembler.cpp
index db396842a9..9f9b0dcfce 100644
--- a/src/codegen/target/arm/assembler.cpp
+++ b/src/codegen/target/arm/assembler.cpp
@@ -989,8 +989,12 @@ class MyAssembler : public Assembler {
                 static_cast<target_uintptr_t*>(e->address),
                 e->callOffset ? dst + e->callOffset->value() + 8 : 0);
       }
-      //       fprintf(stderr, "constant %p at %p\n",
-      //       reinterpret_cast<void*>(e->constant->value()), e->address);
+      if (false) {
+        fprintf(stderr,
+                "constant %p at %p\n",
+                reinterpret_cast<void*>(e->constant->value()),
+                e->address);
+      }
     }
   }
 
diff --git a/src/compile.cpp b/src/compile.cpp
index 99733fb4b6..7a546feb3a 100644
--- a/src/compile.cpp
+++ b/src/compile.cpp
@@ -450,20 +450,18 @@ void nextFrame(MyThread* t,
     methodIsMostRecent = false;
   }
 
-  // fprintf(stderr, "nextFrame %s.%s%s target %s.%s%s ip %p sp %p\n",
-  //         method->class_()->name()->body().begin(),
-  //         method->name()->body().begin(),
-  //         method->spec()->body().begin(),
-  //         target
-  //         ? &byteArrayBody(t, target->class_()->name(), 0)
-  //         : 0,
-  //         target
-  //         ? &byteArrayBody(t, target->name(), 0)
-  //         : 0,
-  //         target
-  //         ? &byteArrayBody(t, target->spec(), 0)
-  //         : 0,
-  //         *ip, *sp);
+  if (false) {
+    fprintf(stderr,
+            "nextFrame %s.%s%s target %s.%s%s ip %p sp %p\n",
+            method->class_()->name()->body().begin(),
+            method->name()->body().begin(),
+            method->spec()->body().begin(),
+            target ? target->class_()->name()->body().begin() : 0,
+            target ? target->name()->body().begin() : 0,
+            target ? target->spec()->body().begin() : 0,
+            *ip,
+            *sp);
+  }
 
   t->arch->nextFrame(reinterpret_cast<void*>(start),
                      code->compiledSize(),
@@ -474,7 +472,9 @@ void nextFrame(MyThread* t,
                      ip,
                      sp);
 
-  // fprintf(stderr, "next frame ip %p sp %p\n", *ip, *sp);
+  if (false) {
+    fprintf(stderr, "next frame ip %p sp %p\n", *ip, *sp);
+  }
 }
 
 void* getIp(MyThread* t, void* ip, void* stack)
@@ -556,7 +556,9 @@ class MyStackWalker : public Processor::StackWalker {
   bool valid()
   {
     while (true) {
-      //       fprintf(stderr, "state: %d\n", state);
+      if (false) {
+        fprintf(stderr, "state: %d\n", state);
+      }
       switch (state) {
       case Start:
         if (trace and trace->nativeMethod) {
@@ -638,9 +640,12 @@ class MyStackWalker : public Processor::StackWalker {
 
   virtual GcMethod* method()
   {
-    //     fprintf(stderr, "method %s.%s\n", &byteArrayBody
-    //             (t, className(t, methodClass(t, method_)), 0),
-    //             &byteArrayBody(t, methodName(t, method_), 0));
+    if (false) {
+      fprintf(stderr,
+              "method %s.%s\n",
+              method_->class_()->name()->body().begin(),
+              method_->name()->body().begin());
+    }
     return method_;
   }
 
@@ -3924,8 +3929,6 @@ loop:
               c->threadRegister());
     }
 
-    //     fprintf(stderr, "ip: %d map: %ld\n", ip, *(frame->map));
-
     if (DebugInstructions) {
       unsigned startingIp = ip;
       fprintf(stderr, " stack: [");
@@ -6991,10 +6994,13 @@ void compile(MyThread* t, Context* context)
 {
   avian::codegen::Compiler* c = context->compiler;
 
-  //   fprintf(stderr, "compiling %s.%s%s\n",
-  //           context->method->class_()->name()->body().begin(),
-  //           context->method->name()->body().begin(),
-  //           context->method->spec()->body().begin());
+  if (false) {
+    fprintf(stderr,
+            "compiling %s.%s%s\n",
+            context->method->class_()->name()->body().begin(),
+            context->method->name()->body().begin(),
+            context->method->spec()->body().begin());
+  }
 
   unsigned footprint = context->method->parameterFootprint();
   unsigned locals = localSize(t, context->method);
@@ -9527,8 +9533,13 @@ void fixupHeap(MyThread* t UNUSED,
 
           if (number) {
             *p = reinterpret_cast<uintptr_t>(heap + (number - 1)) | mark;
-            // fprintf(stderr, "fixup %d: %d 0x%x\n", index,
-            // static_cast<unsigned>(number), static_cast<unsigned>(*p));
+            if (false) {
+              fprintf(stderr,
+                      "fixup %d: %d 0x%x\n",
+                      index,
+                      static_cast<unsigned>(number),
+                      static_cast<unsigned>(*p));
+            }
           } else {
             *p = mark;
           }
@@ -9675,14 +9686,19 @@ void boot(MyThread* t, BootImage* image, uint8_t* code)
 
   t->heapImage = p->heapImage = heap;
 
-  // fprintf(stderr, "heap from %p to %p\n",
-  //         heap, heap + ceilingDivide(image->heapSize, BytesPerWord));
+  if (false) {
+    fprintf(stderr,
+            "heap from %p to %p\n",
+            heap,
+            heap + ceilingDivide(image->heapSize, BytesPerWord));
+  }
 
   t->codeImage = p->codeImage = code;
   p->codeImageSize = image->codeSize;
 
-  // fprintf(stderr, "code from %p to %p\n",
-  //         code, code + image->codeSize);
+  if (false) {
+    fprintf(stderr, "code from %p to %p\n", code, code + image->codeSize);
+  }
 
   if (not image->initialized) {
     fixupHeap(t, heapMap, heapMapSizeInWords, heap);
diff --git a/src/jnienv.cpp b/src/jnienv.cpp
index 58089d1e62..1f067b0268 100644
--- a/src/jnienv.cpp
+++ b/src/jnienv.cpp
@@ -3088,9 +3088,14 @@ uint64_t registerNatives(Thread* t, uintptr_t* arguments)
         // case, but that would prevent using a code shrinker like
         // ProGuard effectively.  Instead, we just ignore it.
 
-        // fprintf(stderr, "not found: %s.%s%s\n", &byteArrayBody(t,
-        // className(t, (*c)->vmClass()), 0), methods[i].name, sig);
-        // abort(t);
+        if (false) {
+          fprintf(stderr,
+                  "not found: %s.%s%s\n",
+                  (*c)->vmClass()->name()->body().begin(),
+                  methods[i].name,
+                  sig);
+          abort(t);
+        }
       } else {
         registerNative(t, method, methods[i].function);
       }
diff --git a/src/machine.cpp b/src/machine.cpp
index 82d95a6629..a9af32e917 100644
--- a/src/machine.cpp
+++ b/src/machine.cpp
@@ -3536,16 +3536,18 @@ object findInTable(Thread* t,
       }
     }
 
-    //     fprintf(stderr, "%s %s not in\n",
-    //             name->body().begin(),
-    //             spec->body().begin();
+    if (false) {
+      fprintf(
+          stderr, "%s %s not in\n", name->body().begin(), spec->body().begin());
 
-    //     for (unsigned i = 0; i < arrayLength(t, table); ++i) {
-    //       object o = arrayBody(t, table, i);
-    //       fprintf(stderr, "\t%s %s\n",
-    //               &byteArrayBody(t, getName(t, o), 0),
-    //               &byteArrayBody(t, getSpec(t, o), 0));
-    //     }
+      for (unsigned i = 0; i < table->length(); ++i) {
+        object o = table->body()[i];
+        fprintf(stderr,
+                "\t%s %s\n",
+                getName(t, o)->body().begin(),
+                getSpec(t, o)->body().begin());
+      }
+    }
   }
 
   return 0;
diff --git a/src/tools/bootimage-generator/main.cpp b/src/tools/bootimage-generator/main.cpp
index 70ce2e5459..bdb4102c00 100644
--- a/src/tools/bootimage-generator/main.cpp
+++ b/src/tools/bootimage-generator/main.cpp
@@ -354,7 +354,9 @@ GcTriple* makeCodeImage(Thread* t,
 
     if (endsWith(".class", name, nameSize)
         and (className == 0 or strncmp(name, className, nameSize - 6) == 0)) {
-      // fprintf(stderr, "pass 1 %.*s\n", nameSize - 6, name);
+      if (false) {
+        fprintf(stderr, "pass 1 %.*s\n", nameSize - 6, name);
+      }
       GcClass* c
           = resolveSystemClass(t,
                                roots(t)->bootLoader(),
@@ -690,7 +692,9 @@ GcTriple* makeCodeImage(Thread* t,
 
     if (endsWith(".class", name, nameSize)
         and (className == 0 or strncmp(name, className, nameSize - 6) == 0)) {
-      // fprintf(stderr, "pass 2 %.*s\n", nameSize - 6, name);
+      if (false) {
+        fprintf(stderr, "pass 2 %.*s\n", nameSize - 6, name);
+      }
       GcClass* c = 0;
       PROTECT(t, c);