diff --git a/cache.h b/cache.h
index feb49b788f..8140763008 100644
--- a/cache.h
+++ b/cache.h
@@ -734,7 +734,6 @@ extern int git_config_set_multivar(const char *, const char *, const char *, int
 extern int git_config_rename_section(const char *, const char *);
 extern const char *git_etc_gitconfig(void);
 extern int check_repository_format_version(const char *var, const char *value, void *cb);
-extern int git_env_bool(const char *, int);
 extern int git_config_system(void);
 extern int git_config_global(void);
 extern int config_error_nonbool(const char *);
diff --git a/config.c b/config.c
index c2f2bbb000..04d97e3d0b 100644
--- a/config.c
+++ b/config.c
@@ -549,7 +549,7 @@ const char *git_etc_gitconfig(void)
 	return system_wide;
 }
 
-int git_env_bool(const char *k, int def)
+static int git_env_bool(const char *k, int def)
 {
 	const char *v = getenv(k);
 	return v ? git_config_bool(k, v) : def;