diff --git a/api/pdfrenderer.cpp b/api/pdfrenderer.cpp
index 1e6971a63c..912d977027 100644
--- a/api/pdfrenderer.cpp
+++ b/api/pdfrenderer.cpp
@@ -159,7 +159,7 @@ CIDToGIDMap.
 
 OK there is a small problem there, if I use GID 0 then Acrobat gets
 upset about it and complains it cannot extract the font. If I set the
-CIDToGIDMap so that all the entries are 1 instead, its happy. Totally
+CIDToGIDMap so that all the entries are 1 instead, it's happy. Totally
 mad......
 
 */
@@ -169,15 +169,15 @@ namespace tesseract {
 // Use for PDF object fragments. Must be large enough
 // to hold a colormap with 256 colors in the verbose
 // PDF representation.
-const int kBasicBufSize = 2048;
+static const int kBasicBufSize = 2048;
 
 // If the font is 10 pts, nominal character width is 5 pts
-const int kCharWidth = 2;
+static const int kCharWidth = 2;
 
 // Used for memory allocation. A codepoint must take no more than this
 // many bytes, when written in the PDF way. e.g. "<0063>" for the
 // letter 'c'
-const int kMaxBytesPerCodepoint = 20;
+static const int kMaxBytesPerCodepoint = 20;
 
 /**********************************************************************
  * PDF Renderer interface implementation
@@ -309,18 +309,19 @@ void ClipBaseline(int ppi, int x1, int y1, int x2, int y2,
     *line_y1 = *line_y2 = (y1 + y2) / 2;
 }
 
-bool CodepointToUtf16be(int code, char *utf16) {
+bool CodepointToUtf16be(int code, char utf16[kMaxBytesPerCodepoint]) {
   if ((code > 0xD7FF && code < 0xE000) || code > 0x10FFFF) {
     tprintf("Dropping invalid codepoint %d\n", code);
     return false;
   }
   if (code < 0x10000) {
-    snprintf(utf16, sizeof(utf16), "%04X", code);
+    snprintf(utf16, kMaxBytesPerCodepoint, "%04X", code);
   } else {
     int a = code - 0x010000;
     int high_surrogate = (0x03FF & (a >> 10)) + 0xD800;
     int low_surrogate = (0x03FF & a) + 0xDC00;
-    snprintf(utf16, sizeof(utf16), "%04X%04X", high_surrogate, low_surrogate);
+    snprintf(utf16, kMaxBytesPerCodepoint,
+             "%04X%04X", high_surrogate, low_surrogate);
   }
   return true;
 }