diff --git a/src/api/pdfrenderer.cpp b/src/api/pdfrenderer.cpp
index 20abf9b7..0ddcd306 100644
--- a/src/api/pdfrenderer.cpp
+++ b/src/api/pdfrenderer.cpp
@@ -182,9 +182,9 @@ static const int kMaxBytesPerCodepoint = 20;
 
 TessPDFRenderer::TessPDFRenderer(const char *outputbase, const char *datadir,
                                  bool textonly)
-    : TessResultRenderer(outputbase, "pdf") {
+    : TessResultRenderer(outputbase, "pdf"),
+      datadir_(datadir) {
   obj_  = 0;
-  datadir_ = datadir;
   textonly_ = textonly;
   offsets_.push_back(0);
 }
@@ -654,7 +654,7 @@ bool TessPDFRenderer::BeginDocumentHandler() {
   if (n >= sizeof(buf)) return false;
   AppendPDFObject(buf);
 
-  n = snprintf(buf, sizeof(buf), "%s/pdf.ttf", datadir_);
+  n = snprintf(buf, sizeof(buf), "%s/pdf.ttf", datadir_.c_str());
   if (n >= sizeof(buf)) return false;
   FILE *fp = fopen(buf, "rb");
   if (!fp) {
diff --git a/src/api/renderer.h b/src/api/renderer.h
index 30da61d2..0a723176 100644
--- a/src/api/renderer.h
+++ b/src/api/renderer.h
@@ -21,6 +21,7 @@
 // To avoid collision with other typenames include the ABSOLUTE MINIMUM
 // complexity of includes here. Use forward declarations wherever possible
 // and hide includes of complex types in baseapi.cpp.
+#include <string>               // for std::string
 #include "genericvector.h"
 #include "platform.h"
 
@@ -202,7 +203,7 @@ class TESS_API TessPDFRenderer : public TessResultRenderer {
   long int obj_;                     // counter for PDF objects
   GenericVector<long int> offsets_;  // offset of every PDF object in bytes
   GenericVector<long int> pages_;    // object number for every /Page object
-  const char *datadir_;              // where to find the custom font
+  std::string datadir_;              // where to find the custom font
   bool textonly_;                    // skip images if set
   // Bookkeeping only. DIY = Do It Yourself.
   void AppendPDFObjectDIY(size_t objectsize);