diff --git a/src/libcmd/markdown.cc b/src/libcmd/markdown.cc
index 668a07763..8b3bbc1b5 100644
--- a/src/libcmd/markdown.cc
+++ b/src/libcmd/markdown.cc
@@ -1,6 +1,7 @@
 #include "markdown.hh"
 #include "util.hh"
 #include "finally.hh"
+#include "terminal.hh"
 
 #include <sys/queue.h>
 #include <lowdown.h>
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index e13d1cb93..ac50351ad 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -8,6 +8,7 @@
 #include "fetchers.hh"
 #include "finally.hh"
 #include "fetch-settings.hh"
+#include "terminal.hh"
 
 namespace nix {
 
diff --git a/src/libexpr/print.cc b/src/libexpr/print.cc
index 231bde0a0..c56b0e72e 100644
--- a/src/libexpr/print.cc
+++ b/src/libexpr/print.cc
@@ -9,6 +9,7 @@
 #include "english.hh"
 #include "signals.hh"
 #include "eval.hh"
+#include "terminal.hh"
 
 namespace nix {
 
diff --git a/src/libmain/progress-bar.cc b/src/libmain/progress-bar.cc
index 1a68daca2..f3700f103 100644
--- a/src/libmain/progress-bar.cc
+++ b/src/libmain/progress-bar.cc
@@ -3,6 +3,7 @@
 #include "sync.hh"
 #include "store-api.hh"
 #include "names.hh"
+#include "terminal.hh"
 
 #include <atomic>
 #include <map>
diff --git a/src/libutil/error.cc b/src/libutil/error.cc
index fe73ffc56..f780aabef 100644
--- a/src/libutil/error.cc
+++ b/src/libutil/error.cc
@@ -1,6 +1,7 @@
 #include "environment-variables.hh"
 #include "error.hh"
 #include "position.hh"
+#include "terminal.hh"
 
 #include <iostream>
 #include <optional>
diff --git a/src/libutil/logging.cc b/src/libutil/logging.cc
index 8e4828be4..731d1034d 100644
--- a/src/libutil/logging.cc
+++ b/src/libutil/logging.cc
@@ -4,6 +4,7 @@
 #include "config.hh"
 #include "source-path.hh"
 #include "position.hh"
+#include "terminal.hh"
 
 #include <atomic>
 #include <nlohmann/json.hpp>
diff --git a/src/libutil/meson.build b/src/libutil/meson.build
index 01b3e24b7..c890911e9 100644
--- a/src/libutil/meson.build
+++ b/src/libutil/meson.build
@@ -30,6 +30,7 @@ libutil_sources = files(
   'source-path.cc',
   'suggestions.cc',
   'tarfile.cc',
+  'terminal.cc',
   'thread-pool.cc',
   'url.cc',
   'url-name.cc',
@@ -90,6 +91,7 @@ libutil_headers = files(
   'suggestions.hh',
   'sync.hh',
   'tarfile.hh',
+  'terminal.hh',
   'thread-pool.hh',
   'topo-sort.hh',
   'types.hh',
diff --git a/src/libutil/signals.cc b/src/libutil/signals.cc
index 41fdc9dc8..c0e66f6ed 100644
--- a/src/libutil/signals.cc
+++ b/src/libutil/signals.cc
@@ -2,6 +2,7 @@
 #include "util.hh"
 #include "error.hh"
 #include "sync.hh"
+#include "terminal.hh"
 
 #include <thread>
 
diff --git a/src/libutil/suggestions.cc b/src/libutil/suggestions.cc
index 9510a5f0c..63dcf84b5 100644
--- a/src/libutil/suggestions.cc
+++ b/src/libutil/suggestions.cc
@@ -1,7 +1,9 @@
 #include "suggestions.hh"
 #include "ansicolor.hh"
-#include "util.hh"
+#include "terminal.hh"
+
 #include <algorithm>
+#include <ostream>
 
 namespace nix {
 
diff --git a/src/libutil/terminal.cc b/src/libutil/terminal.cc
new file mode 100644
index 000000000..b58331d04
--- /dev/null
+++ b/src/libutil/terminal.cc
@@ -0,0 +1,104 @@
+#include "terminal.hh"
+#include "environment-variables.hh"
+#include "sync.hh"
+
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+namespace nix {
+
+bool shouldANSI()
+{
+    return isatty(STDERR_FILENO)
+        && getEnv("TERM").value_or("dumb") != "dumb"
+        && !(getEnv("NO_COLOR").has_value() || getEnv("NOCOLOR").has_value());
+}
+
+std::string filterANSIEscapes(std::string_view s, bool filterAll, unsigned int width)
+{
+    std::string t, e;
+    size_t w = 0;
+    auto i = s.begin();
+
+    while (w < (size_t) width && i != s.end()) {
+
+        if (*i == '\e') {
+            std::string e;
+            e += *i++;
+            char last = 0;
+
+            if (i != s.end() && *i == '[') {
+                e += *i++;
+                // eat parameter bytes
+                while (i != s.end() && *i >= 0x30 && *i <= 0x3f) e += *i++;
+                // eat intermediate bytes
+                while (i != s.end() && *i >= 0x20 && *i <= 0x2f) e += *i++;
+                // eat final byte
+                if (i != s.end() && *i >= 0x40 && *i <= 0x7e) e += last = *i++;
+            } else {
+                if (i != s.end() && *i >= 0x40 && *i <= 0x5f) e += *i++;
+            }
+
+            if (!filterAll && last == 'm')
+                t += e;
+        }
+
+        else if (*i == '\t') {
+            i++; t += ' '; w++;
+            while (w < (size_t) width && w % 8) {
+                t += ' '; w++;
+            }
+        }
+
+        else if (*i == '\r' || *i == '\a')
+            // do nothing for now
+            i++;
+
+        else {
+            w++;
+            // Copy one UTF-8 character.
+            if ((*i & 0xe0) == 0xc0) {
+                t += *i++;
+                if (i != s.end() && ((*i & 0xc0) == 0x80)) t += *i++;
+            } else if ((*i & 0xf0) == 0xe0) {
+                t += *i++;
+                if (i != s.end() && ((*i & 0xc0) == 0x80)) {
+                    t += *i++;
+                    if (i != s.end() && ((*i & 0xc0) == 0x80)) t += *i++;
+                }
+            } else if ((*i & 0xf8) == 0xf0) {
+                t += *i++;
+                if (i != s.end() && ((*i & 0xc0) == 0x80)) {
+                    t += *i++;
+                    if (i != s.end() && ((*i & 0xc0) == 0x80)) {
+                        t += *i++;
+                        if (i != s.end() && ((*i & 0xc0) == 0x80)) t += *i++;
+                    }
+                }
+            } else
+                t += *i++;
+        }
+    }
+
+    return t;
+}
+
+static Sync<std::pair<unsigned short, unsigned short>> windowSize{{0, 0}};
+
+void updateWindowSize()
+{
+    struct winsize ws;
+    if (ioctl(2, TIOCGWINSZ, &ws) == 0) {
+        auto windowSize_(windowSize.lock());
+        windowSize_->first = ws.ws_row;
+        windowSize_->second = ws.ws_col;
+    }
+}
+
+
+std::pair<unsigned short, unsigned short> getWindowSize()
+{
+    return *windowSize.lock();
+}
+
+}
diff --git a/src/libutil/terminal.hh b/src/libutil/terminal.hh
new file mode 100644
index 000000000..43df5bd70
--- /dev/null
+++ b/src/libutil/terminal.hh
@@ -0,0 +1,40 @@
+#pragma once
+///@file
+
+#include <limits>
+#include <string>
+
+namespace nix {
+
+/**
+ * Determine whether ANSI escape sequences are appropriate for the
+ * present output.
+ */
+bool shouldANSI();
+
+/**
+ * Truncate a string to 'width' printable characters. If 'filterAll'
+ * is true, all ANSI escape sequences are filtered out. Otherwise,
+ * some escape sequences (such as colour setting) are copied but not
+ * included in the character count. Also, tabs are expanded to
+ * spaces.
+ */
+std::string filterANSIEscapes(std::string_view s,
+    bool filterAll = false,
+    unsigned int width = std::numeric_limits<unsigned int>::max());
+
+/**
+ * Recalculate the window size, updating a global variable. Used in the
+ * `SIGWINCH` signal handler.
+ */
+void updateWindowSize();
+
+/**
+ * @return the number of rows and columns of the terminal.
+ *
+ * The value is cached so this is quick. The cached result is computed
+ * by `updateWindowSize()`.
+ */
+std::pair<unsigned short, unsigned short> getWindowSize();
+
+}
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 97d53ca63..63d9e5248 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1436,83 +1436,6 @@ void ignoreException(Verbosity lvl)
     } catch (...) { }
 }
 
-bool shouldANSI()
-{
-    return isatty(STDERR_FILENO)
-        && getEnv("TERM").value_or("dumb") != "dumb"
-        && !(getEnv("NO_COLOR").has_value() || getEnv("NOCOLOR").has_value());
-}
-
-std::string filterANSIEscapes(std::string_view s, bool filterAll, unsigned int width)
-{
-    std::string t, e;
-    size_t w = 0;
-    auto i = s.begin();
-
-    while (w < (size_t) width && i != s.end()) {
-
-        if (*i == '\e') {
-            std::string e;
-            e += *i++;
-            char last = 0;
-
-            if (i != s.end() && *i == '[') {
-                e += *i++;
-                // eat parameter bytes
-                while (i != s.end() && *i >= 0x30 && *i <= 0x3f) e += *i++;
-                // eat intermediate bytes
-                while (i != s.end() && *i >= 0x20 && *i <= 0x2f) e += *i++;
-                // eat final byte
-                if (i != s.end() && *i >= 0x40 && *i <= 0x7e) e += last = *i++;
-            } else {
-                if (i != s.end() && *i >= 0x40 && *i <= 0x5f) e += *i++;
-            }
-
-            if (!filterAll && last == 'm')
-                t += e;
-        }
-
-        else if (*i == '\t') {
-            i++; t += ' '; w++;
-            while (w < (size_t) width && w % 8) {
-                t += ' '; w++;
-            }
-        }
-
-        else if (*i == '\r' || *i == '\a')
-            // do nothing for now
-            i++;
-
-        else {
-            w++;
-            // Copy one UTF-8 character.
-            if ((*i & 0xe0) == 0xc0) {
-                t += *i++;
-                if (i != s.end() && ((*i & 0xc0) == 0x80)) t += *i++;
-            } else if ((*i & 0xf0) == 0xe0) {
-                t += *i++;
-                if (i != s.end() && ((*i & 0xc0) == 0x80)) {
-                    t += *i++;
-                    if (i != s.end() && ((*i & 0xc0) == 0x80)) t += *i++;
-                }
-            } else if ((*i & 0xf8) == 0xf0) {
-                t += *i++;
-                if (i != s.end() && ((*i & 0xc0) == 0x80)) {
-                    t += *i++;
-                    if (i != s.end() && ((*i & 0xc0) == 0x80)) {
-                        t += *i++;
-                        if (i != s.end() && ((*i & 0xc0) == 0x80)) t += *i++;
-                    }
-                }
-            } else
-                t += *i++;
-        }
-    }
-
-    return t;
-}
-
-
 constexpr char base64Chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
 std::string base64Encode(std::string_view s)
@@ -1630,25 +1553,6 @@ std::pair<std::string_view, std::string_view> getLine(std::string_view s)
 
 //////////////////////////////////////////////////////////////////////
 
-static Sync<std::pair<unsigned short, unsigned short>> windowSize{{0, 0}};
-
-
-void updateWindowSize()
-{
-    struct winsize ws;
-    if (ioctl(2, TIOCGWINSZ, &ws) == 0) {
-        auto windowSize_(windowSize.lock());
-        windowSize_->first = ws.ws_row;
-        windowSize_->second = ws.ws_col;
-    }
-}
-
-
-std::pair<unsigned short, unsigned short> getWindowSize()
-{
-    return *windowSize.lock();
-}
-
 
 rlim_t savedStackSize = 0;
 
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 151da25b9..1ce7e8312 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -726,23 +726,6 @@ constexpr char treeLast[] = "└───";
 constexpr char treeLine[] = "│   ";
 constexpr char treeNull[] = "    ";
 
-/**
- * Determine whether ANSI escape sequences are appropriate for the
- * present output.
- */
-bool shouldANSI();
-
-/**
- * Truncate a string to 'width' printable characters. If 'filterAll'
- * is true, all ANSI escape sequences are filtered out. Otherwise,
- * some escape sequences (such as colour setting) are copied but not
- * included in the character count. Also, tabs are expanded to
- * spaces.
- */
-std::string filterANSIEscapes(std::string_view s,
-    bool filterAll = false,
-    unsigned int width = std::numeric_limits<unsigned int>::max());
-
 
 /**
  * Base64 encoding/decoding.
@@ -840,14 +823,6 @@ struct MaintainCount
 };
 
 
-/**
- * @return the number of rows and columns of the terminal.
- */
-std::pair<unsigned short, unsigned short> getWindowSize();
-
-void updateWindowSize();
-
-
 /**
  * Used in various places.
  */
diff --git a/tests/unit/libutil/tests.cc b/tests/unit/libutil/tests.cc
index 720370066..787f79093 100644
--- a/tests/unit/libutil/tests.cc
+++ b/tests/unit/libutil/tests.cc
@@ -1,5 +1,6 @@
 #include "util.hh"
 #include "types.hh"
+#include "terminal.hh"
 
 #include <limits.h>
 #include <gtest/gtest.h>