diff --git a/include/util/format.hpp b/include/util/format.hpp
index 74c504fe..0147701b 100644
--- a/include/util/format.hpp
+++ b/include/util/format.hpp
@@ -1,9 +1,84 @@
 #pragma once
 
-#include <sstream>
+#include <fmt/format.h>
 
-namespace waybar::util {
+class pow_format {
+  public:
+    pow_format(long long val, std::string&& unit, bool binary = false):
+      val_(val), unit_(unit), binary_(binary) { };
 
-std::string pow_format(unsigned long long value, const std::string &unit, bool binary = false);
+    long long val_;
+    std::string unit_;
+    bool binary_;
+};
 
+
+namespace fmt {
+  template <>
+    struct formatter<pow_format> {
+      char spec = 0;
+      int width = 0;
+
+      template <typename ParseContext>
+        constexpr auto parse(ParseContext& ctx) -> decltype (ctx.begin()) {
+          auto it = ctx.begin(), end = ctx.end();
+          if (it != end && *it == ':') ++it;
+          if (*it == '>' || *it == '<' || *it == '=') {
+            spec = *it;
+            ++it;
+          }
+          if (it == end || *it == '}') return it;
+          if ('0' <= *it && *it <= '9') {
+            // We ignore it for now, but keep it for compatibility with
+            // existing configs where the format for pow_format'ed numbers was
+            // 'string' and specifications such as {:>9} were valid.
+            // The rationale for ignoring it is that the only reason to specify
+            // an alignment and a with is to get a fixed width bar, and ">" is
+            // sufficient in this implementation.
+            width = parse_nonnegative_int(it, end, ctx);
+          }
+          return it;
+        }
+
+      template<class FormatContext>
+        auto format(const pow_format& s, FormatContext &ctx) -> decltype (ctx.out()) {
+          const char* units[] = { "", "k",  "M",  "G",  "T",  "P",  nullptr};
+
+          auto base = s.binary_ ? 1024ull : 1000ll;
+          auto fraction = (double) s.val_;
+
+          int pow;
+          for (pow = 0; units[pow+1] != nullptr && fraction / base >= 1; ++pow) {
+            fraction /= base;
+          }
+
+          auto max_width = 4                  // coeff in {:.3g} format
+                         + 1                  // prefix from units array
+                         + s.binary_          // for the 'i' in GiB.
+                         + s.unit_.length();
+
+          const char * format;
+          std::string string;
+          switch (spec) {
+            case '>':
+              return format_to(ctx.out(), "{:>{}}", fmt::format("{}", s), max_width);
+            case '<':
+              return format_to(ctx.out(), "{:<{}}", fmt::format("{}", s), max_width);
+            case '=':
+              format = "{coefficient:<4.3g}{padding}{prefix}{unit}";
+              break;
+            case 0:
+            default:
+              format = "{coefficient:.3g}{prefix}{unit}";
+              break;
+          }
+          return format_to(ctx.out(), format
+              , fmt::arg("coefficient", fraction)
+              , fmt::arg("prefix", std::string() + units[pow] + ((s.binary_ && pow) ? "i" : ""))
+              , fmt::arg("unit", s.unit_)
+              , fmt::arg("padding", pow ? "" : s.binary_ ? "  " : " ")
+            );
+        }
+    };
 }
+
diff --git a/meson.build b/meson.build
index b0d99b93..a9d44eeb 100644
--- a/meson.build
+++ b/meson.build
@@ -91,7 +91,6 @@ src_files = files(
     'src/modules/disk.cpp',
     'src/modules/idle_inhibitor.cpp',
     'src/modules/temperature.cpp',
-    'src/util/format.cpp',
     'src/main.cpp',
     'src/bar.cpp',
     'src/client.cpp'
diff --git a/src/modules/disk.cpp b/src/modules/disk.cpp
index 859a45a2..811fe729 100644
--- a/src/modules/disk.cpp
+++ b/src/modules/disk.cpp
@@ -44,15 +44,33 @@ auto waybar::modules::Disk::update() -> void {
     return;
   }
 
-  label_.set_markup(fmt::format(format_,
-        stats.f_bavail * 100 / stats.f_blocks,
-        fmt::arg("free", pow_format(stats.f_bavail * stats.f_bsize, "B", true)),
-        fmt::arg("percentage_free", stats.f_bavail * 100 / stats.f_blocks),
-        fmt::arg("used", pow_format((stats.f_blocks - stats.f_bavail) * stats.f_bsize, "B", true)),
-        fmt::arg("percentage_used", (stats.f_blocks - stats.f_bavail) * 100 / stats.f_blocks)
-  ));
+  auto free = pow_format(stats.f_bavail * stats.f_bsize, "B", true);
+  auto used = pow_format((stats.f_blocks - stats.f_bavail) * stats.f_bsize, "B", true);
+  auto total = pow_format(stats.f_blocks * stats.f_bsize, "B", true);
+
+  label_.set_markup(fmt::format(format_
+      , stats.f_bavail * 100 / stats.f_blocks
+      , fmt::arg("free", free)
+      , fmt::arg("percentage_free", stats.f_bavail * 100 / stats.f_blocks)
+      , fmt::arg("used", used)
+      , fmt::arg("percentage_used", (stats.f_blocks - stats.f_bavail) * 100 / stats.f_blocks)
+      , fmt::arg("total", total)
+      , fmt::arg("path", path_)
+      ));
   if (tooltipEnabled()) {
-    label_.set_tooltip_text(fmt::format("{} used", pow_format(stats.f_bavail * stats.f_bsize, "B", true)));
+    std::string tooltip_format = "{used} used out of {total} on {path} ({percentage_used}%)";
+    if (config_["tooltip-format"].isString()) {
+      tooltip_format = config_["tooltip-format"].asString();
+    }
+    label_.set_tooltip_text(fmt::format(tooltip_format
+      , stats.f_bavail * 100 / stats.f_blocks
+      , fmt::arg("free", free)
+      , fmt::arg("percentage_free", stats.f_bavail * 100 / stats.f_blocks)
+      , fmt::arg("used", used)
+      , fmt::arg("percentage_used", (stats.f_blocks - stats.f_bavail) * 100 / stats.f_blocks)
+      , fmt::arg("total", total)
+      , fmt::arg("path", path_)
+      ));
   }
   event_box_.show();
 }
diff --git a/src/modules/network.cpp b/src/modules/network.cpp
index 3e2fe9cf..ba196cff 100644
--- a/src/modules/network.cpp
+++ b/src/modules/network.cpp
@@ -515,7 +515,7 @@ bool waybar::modules::Network::checkInterface(struct ifinfomsg *rtif, std::strin
   return false;
 }
 
-int waybar::modules::Network::getPreferredIface(int skip_idx, bool wait = true) const {
+int waybar::modules::Network::getPreferredIface(int skip_idx, bool wait) const {
   int ifid = -1;
   if (config_["interface"].isString()) {
     ifid = if_nametoindex(config_["interface"].asCString());
diff --git a/src/util/format.cpp b/src/util/format.cpp
deleted file mode 100644
index 249c8cd8..00000000
--- a/src/util/format.cpp
+++ /dev/null
@@ -1,26 +0,0 @@
-#include <sstream>
-
-namespace waybar::util {
-
-std::string pow_format(unsigned long long value, const std::string &unit, bool binary = false) {
-  auto base = binary ? 1024ull : 1000ull;
-  const char* units[] = { "", "k",  "M",  "G",  "T",  "P",  nullptr};
-  auto fraction = (double) value;
-
-  int pow;
-  for (pow = 0; units[pow+1] != nullptr && fraction / base >= 2; ++pow) {
-    fraction /= base;
-  }
-
-  std::ostringstream ss;
-  if (pow > 0) {
-    auto quotient = (unsigned long long) fraction;
-    auto remainder = (unsigned long long) ((fraction - quotient) * 10);
-    ss << quotient << "." << remainder << units[pow] << (binary ? "i" : "") << unit;
-  } else {
-    ss << value << unit;
-  }
-  return ss.str();
-};
-
-}