diff --git a/libc/src/stdio/printf_core/CMakeLists.txt b/libc/src/stdio/printf_core/CMakeLists.txt
--- a/libc/src/stdio/printf_core/CMakeLists.txt
+++ b/libc/src/stdio/printf_core/CMakeLists.txt
@@ -28,6 +28,7 @@
     string_writer.h
   DEPENDS
     libc.src.string.memory_utils.memcpy_implementation
+    .core_structs
 )
 
 add_object_library(
@@ -38,6 +39,7 @@
     file_writer.h
   DEPENDS
     libc.src.__support.File.file
+    .core_structs
 )
 
 add_object_library(
diff --git a/libc/src/stdio/printf_core/char_converter.h b/libc/src/stdio/printf_core/char_converter.h
--- a/libc/src/stdio/printf_core/char_converter.h
+++ b/libc/src/stdio/printf_core/char_converter.h
@@ -31,7 +31,7 @@
   } else {
     RET_IF_RESULT_NEGATIVE(writer->write(&c, 1));
   }
-  return 0;
+  return WRITE_OK;
 }
 
 } // namespace printf_core
diff --git a/libc/src/stdio/printf_core/core_structs.h b/libc/src/stdio/printf_core/core_structs.h
--- a/libc/src/stdio/printf_core/core_structs.h
+++ b/libc/src/stdio/printf_core/core_structs.h
@@ -78,6 +78,15 @@
     return true;
   }
 };
+
+// This is the value to be returned by conversions when no error has occurred.
+constexpr int WRITE_OK = 0;
+// These are the printf return values for when an error has occurred. They are
+// all negative, and should be distinct.
+constexpr int FILE_WRITE_ERROR = -1;
+constexpr int FILE_STATUS_ERROR = -2;
+constexpr int NULLPTR_WRITE_ERROR = -3;
+
 } // namespace printf_core
 } // namespace __llvm_libc
 
diff --git a/libc/src/stdio/printf_core/file_writer.cpp b/libc/src/stdio/printf_core/file_writer.cpp
--- a/libc/src/stdio/printf_core/file_writer.cpp
+++ b/libc/src/stdio/printf_core/file_writer.cpp
@@ -8,6 +8,7 @@
 
 #include "src/stdio/printf_core/file_writer.h"
 #include "src/__support/File/file.h"
+#include "src/stdio/printf_core/core_structs.h"
 #include <stddef.h>
 
 namespace __llvm_libc {
@@ -16,9 +17,9 @@
 int FileWriter::write(const char *__restrict to_write, size_t len) {
   int written = file->write_unlocked(to_write, len);
   if (written != static_cast<int>(len))
-    written = -1;
+    written = FILE_WRITE_ERROR;
   if (file->error_unlocked())
-    written = -2;
+    written = FILE_STATUS_ERROR;
   return written;
 }
 
diff --git a/libc/src/stdio/printf_core/float_hex_converter.h b/libc/src/stdio/printf_core/float_hex_converter.h
--- a/libc/src/stdio/printf_core/float_hex_converter.h
+++ b/libc/src/stdio/printf_core/float_hex_converter.h
@@ -89,7 +89,7 @@
                         FormatFlags::LEFT_JUSTIFIED))
       RET_IF_RESULT_NEGATIVE(writer->write_chars(' ', padding));
 
-    return 0;
+    return WRITE_OK;
   }
 
   // Handle the exponent for numbers with a 0 exponent
@@ -264,7 +264,7 @@
     RET_IF_RESULT_NEGATIVE(
         writer->write(exp_buffer + exp_cur, EXP_LEN - exp_cur));
   }
-  return 0;
+  return WRITE_OK;
 }
 
 } // namespace printf_core
diff --git a/libc/src/stdio/printf_core/hex_converter.h b/libc/src/stdio/printf_core/hex_converter.h
--- a/libc/src/stdio/printf_core/hex_converter.h
+++ b/libc/src/stdio/printf_core/hex_converter.h
@@ -124,7 +124,7 @@
     if (digits_written > 0)
       RET_IF_RESULT_NEGATIVE(writer->write(buffer + buff_cur, digits_written));
   }
-  return 0;
+  return WRITE_OK;
 }
 
 } // namespace printf_core
diff --git a/libc/src/stdio/printf_core/int_converter.h b/libc/src/stdio/printf_core/int_converter.h
--- a/libc/src/stdio/printf_core/int_converter.h
+++ b/libc/src/stdio/printf_core/int_converter.h
@@ -136,7 +136,7 @@
     if (digits_written > 0)
       RET_IF_RESULT_NEGATIVE(writer->write(buffer + buff_cur, digits_written));
   }
-  return 0;
+  return WRITE_OK;
 }
 
 } // namespace printf_core
diff --git a/libc/src/stdio/printf_core/oct_converter.h b/libc/src/stdio/printf_core/oct_converter.h
--- a/libc/src/stdio/printf_core/oct_converter.h
+++ b/libc/src/stdio/printf_core/oct_converter.h
@@ -102,7 +102,7 @@
     if (num_digits > 0)
       RET_IF_RESULT_NEGATIVE(writer->write(buffer + buff_cur, num_digits));
   }
-  return 0;
+  return WRITE_OK;
 }
 
 } // namespace printf_core
diff --git a/libc/src/stdio/printf_core/ptr_converter.h b/libc/src/stdio/printf_core/ptr_converter.h
--- a/libc/src/stdio/printf_core/ptr_converter.h
+++ b/libc/src/stdio/printf_core/ptr_converter.h
@@ -30,7 +30,7 @@
     hex_conv.conv_val_raw = reinterpret_cast<uintptr_t>(to_conv.conv_val_ptr);
     return convert_hex(writer, hex_conv);
   }
-  return 0;
+  return WRITE_OK;
 }
 
 } // namespace printf_core
diff --git a/libc/src/stdio/printf_core/string_converter.h b/libc/src/stdio/printf_core/string_converter.h
--- a/libc/src/stdio/printf_core/string_converter.h
+++ b/libc/src/stdio/printf_core/string_converter.h
@@ -47,7 +47,7 @@
     RET_IF_RESULT_NEGATIVE(writer->write(
         reinterpret_cast<const char *>(to_conv.conv_val_ptr), string_len));
   }
-  return 0;
+  return WRITE_OK;
 }
 
 } // namespace printf_core
diff --git a/libc/src/stdio/printf_core/string_writer.cpp b/libc/src/stdio/printf_core/string_writer.cpp
--- a/libc/src/stdio/printf_core/string_writer.cpp
+++ b/libc/src/stdio/printf_core/string_writer.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/stdio/printf_core/string_writer.h"
+#include "src/stdio/printf_core/core_structs.h"
 #include "src/string/memory_utils/memcpy_implementations.h"
 #include <stddef.h>
 
@@ -28,7 +29,7 @@
                     size_t len) {
   StringWriter *string_writer = reinterpret_cast<StringWriter *>(raw_pointer);
   string_writer->write(to_write, len);
-  return 0;
+  return WRITE_OK;
 }
 
 } // namespace printf_core
diff --git a/libc/src/stdio/printf_core/write_int_converter.h b/libc/src/stdio/printf_core/write_int_converter.h
--- a/libc/src/stdio/printf_core/write_int_converter.h
+++ b/libc/src/stdio/printf_core/write_int_converter.h
@@ -25,7 +25,7 @@
   // because printf uses negative return values for errors, and -1 and -2 are
   // already in use by the file_writer class for file errors.
   if (to_conv.conv_val_ptr == nullptr)
-    return -3;
+    return NULLPTR_WRITE_ERROR;
 
   int written = writer->get_chars_written();
 
@@ -56,7 +56,7 @@
     *reinterpret_cast<uintmax_t *>(to_conv.conv_val_ptr) = written;
     break;
   }
-  return 0;
+  return WRITE_OK;
 }
 
 } // namespace printf_core