diff --git a/src/fish_key_reader.cpp b/src/fish_key_reader.cpp
index daf90e8e2..28a432096 100644
--- a/src/fish_key_reader.cpp
+++ b/src/fish_key_reader.cpp
@@ -298,7 +298,6 @@ static void setup_and_process_keys(bool continuous_mode) {
     process_input(continuous_mode);
     restore_term_mode();
     restore_term_foreground_process_group();
-    input_destroy();
 }
 
 static bool parse_debug_level_flag() {
diff --git a/src/input.cpp b/src/input.cpp
index 364c6eb70..4d82bc413 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -13,6 +13,7 @@
 #include <termios.h>
 
 #include <algorithm>
+#include <atomic>
 #include <memory>
 #include <string>
 #include <vector>
@@ -153,9 +154,6 @@ static std::vector<terminfo_mapping_t> terminfo_mappings;
 /// List of all terminfo mappings.
 static std::vector<terminfo_mapping_t> mappings;
 
-/// Set to true when the input subsystem has been initialized.
-bool input_initialized = false;
-
 /// Initialize terminfo.
 static void init_input_terminfo();
 
@@ -263,9 +261,15 @@ static int interrupt_handler() {
     return R_NULL;
 }
 
+static std::atomic<bool> input_initialized{false};
+
 /// Set up arrays used by readch to detect escape sequences for special keys and perform related
 /// initializations for our input subsystem.
 void init_input() {
+    ASSERT_IS_MAIN_THREAD();
+    if (input_initialized.load(std::memory_order_relaxed)) return;
+    input_initialized.store(true, std::memory_order_relaxed);
+
     input_common_init(&interrupt_handler);
     init_input_terminfo();
 
@@ -285,14 +289,6 @@ void init_input() {
         input_mapping_add(L"\x1B[C", L"forward-char", DEFAULT_BIND_MODE, DEFAULT_BIND_MODE, false);
         input_mapping_add(L"\x1B[D", L"backward-char", DEFAULT_BIND_MODE, DEFAULT_BIND_MODE, false);
     }
-
-    input_initialized = true;
-}
-
-void input_destroy() {
-    if (!input_initialized) return;
-    input_initialized = false;
-    input_common_destroy();
 }
 
 void input_function_push_arg(wchar_t arg) {
diff --git a/src/input.h b/src/input.h
index 757a243ac..3ae272239 100644
--- a/src/input.h
+++ b/src/input.h
@@ -16,16 +16,10 @@ class environment_t;
 
 wcstring describe_char(wint_t c);
 
-/// Set to true when the input subsytem has been initialized.
-extern bool input_initialized;
-
 /// Set up arrays used by readch to detect escape sequences for special keys and perform related
 /// initializations for our input subsystem.
 void init_input();
 
-/// free up memory used by terminal functions.
-void input_destroy();
-
 /// Read a character from fd 0. Try to convert some escape sequences into character constants, but
 /// do not permanently block the escape character.
 ///
diff --git a/src/input_common.cpp b/src/input_common.cpp
index 1e04176f4..3ebbe92d7 100644
--- a/src/input_common.cpp
+++ b/src/input_common.cpp
@@ -61,8 +61,6 @@ static int (*interrupt_handler)();
 
 void input_common_init(int (*ih)()) { interrupt_handler = ih; }
 
-void input_common_destroy() {}
-
 /// Internal function used by input_common_readch to read one byte from fd 0. This function should
 /// only be called by input_common_readch().
 static wint_t readb() {
diff --git a/src/input_common.h b/src/input_common.h
index c80bf6f97..58d1ac6f6 100644
--- a/src/input_common.h
+++ b/src/input_common.h
@@ -85,9 +85,6 @@ enum {
 /// Init the library.
 void input_common_init(int (*ih)());
 
-/// Free memory used by the library.
-void input_common_destroy();
-
 /// Adjust the escape timeout.
 void update_wait_on_escape_ms(const environment_t &vars);
 
diff --git a/src/reader.cpp b/src/reader.cpp
index 57504dafd..459466b5d 100644
--- a/src/reader.cpp
+++ b/src/reader.cpp
@@ -1731,7 +1731,7 @@ static void reader_interactive_init() {
     // See if we are running interactively.
     pid_t shell_pgid;
 
-    if (!input_initialized) init_input();
+    init_input();
     shell_pgid = getpgrp();
 
     // This should enable job control on fish, even if our parent process did not enable it for us.
@@ -1846,7 +1846,6 @@ static void reader_interactive_init() {
 /// Destroy data for interactive use.
 static void reader_interactive_destroy() {
     outputter_t::stdoutput().set_color(rgb_color_t::reset(), rgb_color_t::reset());
-    input_destroy();
 }
 
 void reader_sanity_check() {