diff --git a/dict/permdawg.cpp b/dict/permdawg.cpp
index 20fb5792..5d9241f6 100644
--- a/dict/permdawg.cpp
+++ b/dict/permdawg.cpp
@@ -195,7 +195,7 @@ void Dict::go_deeper_dawg_fxn(
             strcmp(output_ambig_words_file.string(), "") != 0) {
           if (output_ambig_words_file_ == NULL) {
             output_ambig_words_file_ =
-                fopen(output_ambig_words_file.string(), "w+");
+                fopen(output_ambig_words_file.string(), "wb+");
             if (output_ambig_words_file_ == NULL) {
               tprintf("Failed to open output_ambig_words_file %s\n",
                       output_ambig_words_file.string());
diff --git a/training/ambiguous_words.cpp b/training/ambiguous_words.cpp
index 0c969aef..7f87b373 100644
--- a/training/ambiguous_words.cpp
+++ b/training/ambiguous_words.cpp
@@ -58,7 +58,7 @@ int main(int argc, char** argv) {
   api.Init(tessdata_dir, lang.string(), tesseract::OEM_TESSERACT_ONLY,
            NULL, NULL, &vars_vec, &vars_values, false);
   tesseract::Dict &dict = api.tesseract()->getDict();
-  FILE *input_file = fopen(input_file_str, "r");
+  FILE *input_file = fopen(input_file_str, "rb");
   if (input_file == NULL) {
     tprintf("Failed to open input wordlist file %s\n", input_file_str);
     exit(1);
diff --git a/training/dawg2wordlist.cpp b/training/dawg2wordlist.cpp
index e982d655..82698295 100644
--- a/training/dawg2wordlist.cpp
+++ b/training/dawg2wordlist.cpp
@@ -54,7 +54,7 @@ class WordOutputter {
 int WriteDawgAsWordlist(const UNICHARSET &unicharset,
                         const tesseract::Dawg *dawg,
                         const char *outfile_name) {
-  FILE *out = fopen(outfile_name, "w");
+  FILE *out = fopen(outfile_name, "wb");
   if (out == NULL) {
     tprintf("Could not open %s for writing.\n", outfile_name);
     return 1;