diff --git a/src/openslide-decode-tifflike.c b/src/openslide-decode-tifflike.c
index 632c35e8b..7065099ff 100644
--- a/src/openslide-decode-tifflike.c
+++ b/src/openslide-decode-tifflike.c
@@ -330,9 +330,9 @@ static bool populate_item(struct _openslide_tifflike *tl,
   }
 
   uint64_t count = item->count;
-  int32_t value_size = get_value_size(item->type, &count);
+  uint32_t value_size = get_value_size(item->type, &count);
   g_assert(value_size);
-  ssize_t len = value_size * count;
+  size_t len = value_size * count;
 
   g_autofree void *buf = g_try_malloc(len);
   if (buf == NULL) {
@@ -341,12 +341,12 @@ static bool populate_item(struct _openslide_tifflike *tl,
     return false;
   }
 
-  //g_debug("reading tiff value: len: %"PRId64", offset %"PRIu64, len, item->offset);
+  //g_debug("reading tiff value: len: %"PRIu64", offset %"PRIu64, len, item->offset);
   if (!_openslide_fseek(f, item->offset, SEEK_SET, err)) {
     g_prefix_error(err, "Couldn't seek to read TIFF value: ");
     return false;
   }
-  if (_openslide_fread(f, buf, len) != (size_t) len) {
+  if (_openslide_fread(f, buf, len) != len) {
     g_set_error(err, OPENSLIDE_ERROR, OPENSLIDE_ERROR_FAILED,
                 "Couldn't read TIFF value");
     return false;
diff --git a/src/openslide-features.h b/src/openslide-features.h
index a5328fbf4..43cd2677d 100644
--- a/src/openslide-features.h
+++ b/src/openslide-features.h
@@ -23,26 +23,6 @@
 #define OPENSLIDE_OPENSLIDE_FEATURES_H_
 
 
-#ifndef __cplusplus
-#  ifdef _MSC_VER
-#    ifndef bool
-#      define bool unsigned char
-#    endif
-#    ifndef true
-#      define true 1
-#    endif
-#    ifndef false
-#      define false 0
-#    endif
-#    ifndef __bool_true_false_are_defined
-#      define __bool_true_false_are_defined 1
-#    endif
-#  else
-#    include <stdbool.h>
-#  endif
-#endif
-
-
 // for exporting from shared libraries or DLLs
 #if defined _WIN32
 #  ifdef _OPENSLIDE_BUILDING_DLL
diff --git a/src/openslide.h b/src/openslide.h
index 648607e2d..f9e97720c 100644
--- a/src/openslide.h
+++ b/src/openslide.h
@@ -35,6 +35,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <stdbool.h>
 
 #ifdef __cplusplus
 extern "C" {