diff --git a/gold/plugin.cc b/gold/plugin.cc
index 4cf2f6a..1c33b12 100644
--- a/gold/plugin.cc
+++ b/gold/plugin.cc
@@ -75,10 +75,10 @@ static enum ld_plugin_status
 get_symbols(const void *handle, int nsyms, struct ld_plugin_symbol *syms);
 
 static enum ld_plugin_status
-add_input_file(char *pathname);
+add_input_file(const char *pathname);
 
 static enum ld_plugin_status
-add_input_library(char *pathname);
+add_input_library(const char *pathname);
 
 static enum ld_plugin_status
 message(int level, const char *format, ...);
@@ -421,7 +421,7 @@ Plugin_manager::release_input_file(unsigned int handle)
 // Add a new input file.
 
 ld_plugin_status
-Plugin_manager::add_input_file(char *pathname, bool is_lib)
+Plugin_manager::add_input_file(const char *pathname, bool is_lib)
 {
   Input_file_argument file(pathname,
                            (is_lib
@@ -1023,7 +1023,7 @@ get_symbols(const void * handle, int nsyms, ld_plugin_symbol* syms)
 // Add a new (real) input file generated by a plugin.
 
 static enum ld_plugin_status
-add_input_file(char *pathname)
+add_input_file(const char *pathname)
 {
   gold_assert(parameters->options().has_plugins());
   return parameters->options().plugins()->add_input_file(pathname, false);
@@ -1032,7 +1032,7 @@ add_input_file(char *pathname)
 // Add a new (real) library required by a plugin.
 
 static enum ld_plugin_status
-add_input_library(char *pathname)
+add_input_library(const char *pathname)
 {
   gold_assert(parameters->options().has_plugins());
   return parameters->options().plugins()->add_input_file(pathname, true);
diff --git a/gold/plugin.h b/gold/plugin.h
index c6371ea..99e6d95 100644
--- a/gold/plugin.h
+++ b/gold/plugin.h
@@ -230,7 +230,7 @@ class Plugin_manager
 
   // Add a new input file.
   ld_plugin_status
-  add_input_file(char *pathname, bool is_lib);
+  add_input_file(const char *pathname, bool is_lib);
 
   // Return TRUE if we are in the replacement phase.
   bool
diff --git a/include/plugin-api.h b/include/plugin-api.h
index 5821785..55cfe25 100644
--- a/include/plugin-api.h
+++ b/include/plugin-api.h
@@ -220,13 +220,13 @@ enum ld_plugin_status
 
 typedef
 enum ld_plugin_status
-(*ld_plugin_add_input_file) (char *pathname);
+(*ld_plugin_add_input_file) (const char *pathname);
 
 /* The linker's interface for adding a library that should be searched.  */
 
 typedef
 enum ld_plugin_status
-(*ld_plugin_add_input_library) (char *libname);
+(*ld_plugin_add_input_library) (const char *libname);
 
 /* The linker's interface for issuing a warning or error message.  */