3 files changed, 13 insertions, 3 deletions
diff --git a/Build/source/texk/kpathsea/ChangeLog b/Build/source/texk/kpathsea/ChangeLog
index 52b4e79b673..1feb2ffbb0c 100644
--- a/Build/source/texk/kpathsea/ChangeLog
+++ b/Build/source/texk/kpathsea/ChangeLog
@@ -1,3 +1,9 @@
+2018-02-01  Karl Berry  <karl@freefriends.org>
+
+	* lib.h (KPSE_CNF_P): new macro.
+	* tex-file.c (kpathsea_find_file_generic): use it,
+	for try_std_extension_first.
+
 2018-01-27  Karl Berry  <karl@freefriends.org>
 
 	* readable.h: doc fixes.
diff --git a/Build/source/texk/kpathsea/lib.h b/Build/source/texk/kpathsea/lib.h
index 8c1f8e1ecc4..df380f654d6 100644
--- a/Build/source/texk/kpathsea/lib.h
+++ b/Build/source/texk/kpathsea/lib.h
@@ -122,6 +122,12 @@ extern "C" {
 /* If the environment variable TEST is set, return it; otherwise,
    DEFAULT.  This is useful for paths that use more than one envvar.  */
 #define ENVVAR(test, default) (getenv (test) ? (test) : (default))
+
+/* Return whether a kpse configuration is (some sort of) true.  Check
+   for negation values, so a value like "2" will be true, just in case.  */
+#define KPSE_CNF_P(val) \
+  ((val) && *(val) && *(val) != 'f' && *(val) != '0')
+
 
 /* Return a fresh copy of S1 followed by S2, et al.  */
 extern KPSEDLL string concat (const_string s1, const_string s2);
diff --git a/Build/source/texk/kpathsea/tex-file.c b/Build/source/texk/kpathsea/tex-file.c
index f11753e6244..626e240b82d 100644
--- a/Build/source/texk/kpathsea/tex-file.c
+++ b/Build/source/texk/kpathsea/tex-file.c
@@ -1079,9 +1079,7 @@ kpathsea_find_file_generic (kpathsea kpse, const_string const_name,
   try_std_extension_first
     = kpathsea_var_value (kpse, "try_std_extension_first");
 
-  if (has_any_suffix /* xxx && ! KPSE_CNF_VALUE_P (try_std_extension_first)*/
-      && (try_std_extension_first == NULL || *try_std_extension_first == 'f'
-          || *try_std_extension_first == '0')) {
+  if (has_any_suffix && !KPSE_CNF_P (try_std_extension_first)) {
     target_asis_name (kpse, &target, &count, format, name, use_fontmaps,
                       has_potential_suffix, has_any_suffix);
     target_suffixed_names (kpse, &target, &count, format, name, use_fontmaps,