diff --git a/kernel/io.cc b/kernel/io.cc
index 5331e2ed8..d5d2994b2 100644
--- a/kernel/io.cc
+++ b/kernel/io.cc
@@ -247,7 +247,7 @@ std::string make_temp_dir(std::string template_str)
 #endif
 }
 
-bool check_directory_exists(const std::string& dirname)
+bool check_is_directory(const std::string& dirname)
 {
 #if defined(_WIN32)
 	struct _stat info;
@@ -267,17 +267,26 @@ bool check_directory_exists(const std::string& dirname)
 }
 
 #ifdef _WIN32
-bool check_file_exists(std::string filename, bool)
+bool check_accessible(const std::string& filename, bool)
 {
 	return _access(filename.c_str(), 0) == 0;
 }
 #else
-bool check_file_exists(std::string filename, bool is_exec)
+bool check_accessible(const std::string& filename, bool is_exec)
 {
 	return access(filename.c_str(), is_exec ? X_OK : F_OK) == 0;
 }
 #endif
 
+bool check_file_exists(const std::string& filename, bool is_exec)
+{
+	return check_accessible(filename, is_exec) && !check_is_directory(filename);
+}
+bool check_directory_exists(const std::string& filename, bool is_exec)
+{
+	return check_accessible(filename, is_exec) && check_is_directory(filename);
+}
+
 bool is_absolute_path(std::string filename)
 {
 #ifdef _WIN32
diff --git a/kernel/io.h b/kernel/io.h
index b21d4d9c8..91699d775 100644
--- a/kernel/io.h
+++ b/kernel/io.h
@@ -64,6 +64,23 @@ inline std::string stringf(const char *fmt, ...)
 	return string;
 }
 
+int readsome(std::istream &f, char *s, int n);
+std::string next_token(std::string &text, const char *sep = " \t\r\n", bool long_strings = false);
+std::vector<std::string> split_tokens(const std::string &text, const char *sep = " \t\r\n");
+bool patmatch(const char *pattern, const char *string);
+#if !defined(YOSYS_DISABLE_SPAWN)
+int run_command(const std::string &command, std::function<void(const std::string&)> process_line = std::function<void(const std::string&)>());
+#endif
+std::string get_base_tmpdir();
+std::string make_temp_file(std::string template_str = get_base_tmpdir() + "/yosys_XXXXXX");
+std::string make_temp_dir(std::string template_str = get_base_tmpdir() + "/yosys_XXXXXX");
+bool check_file_exists(const std::string& filename, bool is_exec = false);
+bool check_directory_exists(const std::string& dirname, bool is_exec = false);
+bool is_absolute_path(std::string filename);
+void remove_directory(std::string dirname);
+bool create_directory(const std::string& dirname);
+std::string escape_filename_spaces(const std::string& filename);
+
 YOSYS_NAMESPACE_END
 
 #endif // YOSYS_IO_H
diff --git a/kernel/yosys.cc b/kernel/yosys.cc
index 60b1bef4d..7d0d688fc 100644
--- a/kernel/yosys.cc
+++ b/kernel/yosys.cc
@@ -556,29 +556,29 @@ void init_share_dirname()
 	std::string proc_self_path = proc_self_dirname();
 #  if defined(_WIN32) && !defined(YOSYS_WIN32_UNIX_DIR)
 	std::string proc_share_path = proc_self_path + "share\\";
-	if (check_file_exists(proc_share_path, true)) {
+	if (check_directory_exists(proc_share_path, true)) {
 		yosys_share_dirname = proc_share_path;
 		return;
 	}
 	proc_share_path = proc_self_path + "..\\share\\";
-	if (check_file_exists(proc_share_path, true)) {
+	if (check_directory_exists(proc_share_path, true)) {
 		yosys_share_dirname = proc_share_path;
 		return;
 	}
 #  else
 	std::string proc_share_path = proc_self_path + "share/";
-	if (check_file_exists(proc_share_path, true)) {
+	if (check_directory_exists(proc_share_path, true)) {
 		yosys_share_dirname = proc_share_path;
 		return;
 	}
 	proc_share_path = proc_self_path + "../share/" + proc_program_prefix()+ "yosys/";
-	if (check_file_exists(proc_share_path, true)) {
+	if (check_directory_exists(proc_share_path, true)) {
 		yosys_share_dirname = proc_share_path;
 		return;
 	}
 #    ifdef YOSYS_DATDIR
 	proc_share_path = YOSYS_DATDIR "/";
-	if (check_file_exists(proc_share_path, true)) {
+	if (check_directory_exists(proc_share_path, true)) {
 		yosys_share_dirname = proc_share_path;
 		return;
 	}
diff --git a/kernel/yosys_common.h b/kernel/yosys_common.h
index 16215fb76..e84676bc0 100644
--- a/kernel/yosys_common.h
+++ b/kernel/yosys_common.h
@@ -252,23 +252,6 @@ inline void memhasher() { if (memhasher_active) memhasher_do(); }
 void yosys_banner();
 int ceil_log2(int x) YS_ATTRIBUTE(const);
 
-int readsome(std::istream &f, char *s, int n);
-std::string next_token(std::string &text, const char *sep = " \t\r\n", bool long_strings = false);
-std::vector<std::string> split_tokens(const std::string &text, const char *sep = " \t\r\n");
-bool patmatch(const char *pattern, const char *string);
-#if !defined(YOSYS_DISABLE_SPAWN)
-int run_command(const std::string &command, std::function<void(const std::string&)> process_line = std::function<void(const std::string&)>());
-#endif
-std::string get_base_tmpdir();
-std::string make_temp_file(std::string template_str = get_base_tmpdir() + "/yosys_XXXXXX");
-std::string make_temp_dir(std::string template_str = get_base_tmpdir() + "/yosys_XXXXXX");
-bool check_file_exists(std::string filename, bool is_exec = false);
-bool check_directory_exists(const std::string& dirname);
-bool is_absolute_path(std::string filename);
-void remove_directory(std::string dirname);
-bool create_directory(const std::string& dirname);
-std::string escape_filename_spaces(const std::string& filename);
-
 template<typename T> int GetSize(const T &obj) { return obj.size(); }
 inline int GetSize(RTLIL::Wire *wire);