diff --git a/Makefile b/Makefile
index 20d4aedff053..fb6faf74d984 100644
--- a/Makefile
+++ b/Makefile
@@ -261,20 +261,30 @@ man5dir = $(mandir)/man5
 man7dir = $(mandir)/man7
 man8dir = $(mandir)/man8
 
+ifndef IN_NIX_SHELL
 # M1 macos machines with homebrew will install the native libraries in
 # /opt/homebrew instead of /usr/local, most likely because they
 # emulate x86_64 compatibility via Rosetta, and wanting to keep the
 # libraries separate. This however means we also need to switch out
 # the paths accordingly when we detect we're on an M1 macos machine.
 ifeq ("$(OS)-$(ARCH)", "Darwin-arm64")
-CPATH := /opt/homebrew/include
-LIBRARY_PATH := /opt/homebrew/lib
+CPATH ?= /opt/homebrew/include
+LIBRARY_PATH ?= /opt/homebrew/lib
 else
-CPATH := /usr/local/include
-LIBRARY_PATH := /usr/local/lib
+CPATH ?= /usr/local/include
+LIBRARY_PATH ?= /usr/local/lib
+endif
+endif
+
+ifneq ($(CPATH),)
+CPATH_CFLAGS := -I$(CPATH)
+endif
+ifneq ($(LIBRARY_PATH),)
+LIBRARY_PATH_LDFLAGS := -L$(LIBRARY_PATH)
 endif
 
 # Detect OpenSSL and SQLite paths dynamically using brew --prefix
+ifndef IN_NIX_SHELL
 ifeq ("$(OS)", "Darwin")
 OPENSSL_PREFIX := $(shell brew --prefix openssl@3 2>/dev/null || brew --prefix openssl 2>/dev/null || echo "")
 SQLITE_PREFIX := $(shell brew --prefix sqlite 2>/dev/null || echo "")
@@ -288,9 +298,10 @@ CPPFLAGS += -I$(SQLITE_PREFIX)/include
 PKG_CONFIG_PATH := $(SQLITE_PREFIX)/lib/pkgconfig:$(PKG_CONFIG_PATH)
 endif
 endif
+endif
 
 CPPFLAGS += -DCLN_NEXT_VERSION="\"$(CLN_NEXT_VERSION)\"" -DPKGLIBEXECDIR="\"$(pkglibexecdir)\"" -DBINDIR="\"$(bindir)\"" -DPLUGINDIR="\"$(plugindir)\"" -DCCAN_TAL_NEVER_RETURN_NULL=1
-CFLAGS = $(CPPFLAGS) $(CWARNFLAGS) $(CDEBUGFLAGS) $(COPTFLAGS) -I $(CCANDIR) $(EXTERNAL_INCLUDE_FLAGS) -I . -I$(CPATH) $(SQLITE3_CFLAGS) $(SODIUM_CFLAGS) $(POSTGRES_INCLUDE) $(FEATURES) $(COVFLAGS) $(DEV_CFLAGS) -DSHACHAIN_BITS=48 -DJSMN_PARENT_LINKS $(PIE_CFLAGS) $(COMPAT_CFLAGS) $(CSANFLAGS)
+CFLAGS = $(CPPFLAGS) $(CWARNFLAGS) $(CDEBUGFLAGS) $(COPTFLAGS) -I $(CCANDIR) $(EXTERNAL_INCLUDE_FLAGS) -I . $(CPATH_CFLAGS) $(SQLITE3_CFLAGS) $(SODIUM_CFLAGS) $(POSTGRES_INCLUDE) $(FEATURES) $(COVFLAGS) $(DEV_CFLAGS) -DSHACHAIN_BITS=48 -DJSMN_PARENT_LINKS $(PIE_CFLAGS) $(COMPAT_CFLAGS) $(CSANFLAGS)
 
 # If CFLAGS is already set in the environment of make (to whatever value, it
 # does not matter) then it would export it to subprocesses with the above value
@@ -308,9 +319,9 @@ ifeq ($(STATIC),1)
 # For MacOS, Jacob Rapoport <jacob@rumblemonkey.com> changed this to:
 #  -L/usr/local/lib -lsqlite3 -lz -Wl,-lm -lpthread -ldl $(COVFLAGS)
 # But that doesn't static link.
-LDLIBS = -L$(CPATH) -Wl,-dn $(SQLITE3_LDLIBS) -Wl,-dy -lm -lpthread -ldl $(COVFLAGS)
+LDLIBS = $(LIBRARY_PATH_LDFLAGS) -Wl,-dn $(SQLITE3_LDLIBS) -Wl,-dy -lm -lpthread -ldl $(COVFLAGS)
 else
-LDLIBS = -L$(CPATH) -lm $(SQLITE3_LDLIBS) $(COVFLAGS)
+LDLIBS = $(LIBRARY_PATH_LDFLAGS) -lm $(SQLITE3_LDLIBS) $(COVFLAGS)
 endif
 
 ifeq ($(HAVE_FUNCTION_SECTIONS),1)
diff --git a/configure b/configure
index 0cd88749dc92..588c6d0ad527 100755
--- a/configure
+++ b/configure
@@ -10,14 +10,16 @@ BASE_WARNFLAGS="-Wall -Wundef -Wmissing-prototypes -Wmissing-declarations -Wstri
 
 OS=$(uname -s)
 ARCH=$(uname -m)
-if [ "$OS-$ARCH" = "Darwin-arm64" ]; then
-CPATH=/opt/homebrew/include
-LIBRARY_PATH=/opt/homebrew/lib
-export PKG_CONFIG_PATH=${PKG_CONFIG_PATH}:/opt/homebrew/opt/sqlite/lib/pkgconfig
-else
-CPATH=/usr/local/lib
-LIBRARY_PATH=/usr/local/lib
-export PKG_CONFIG_PATH=${PKG_CONFIG_PATH}:/usr/local/opt/sqlite/lib/pkgconfig
+if [ -z "$IN_NIX_SHELL" ]; then
+    if [ "$OS-$ARCH" = "Darwin-arm64" ]; then
+	CPATH=${CPATH:-/opt/homebrew/include}
+	LIBRARY_PATH=${LIBRARY_PATH:-/opt/homebrew/lib}
+	export PKG_CONFIG_PATH=${PKG_CONFIG_PATH}:/opt/homebrew/opt/sqlite/lib/pkgconfig
+    else
+	CPATH=${CPATH:-/usr/local/include}
+	LIBRARY_PATH=${LIBRARY_PATH:-/usr/local/lib}
+	export PKG_CONFIG_PATH=${PKG_CONFIG_PATH}:/usr/local/opt/sqlite/lib/pkgconfig
+    fi
 fi
 
 : ${PKG_CONFIG=pkg-config}
@@ -432,7 +434,11 @@ fi
 # Clean up on exit.
 trap "rm -f $CONFIG_VAR_FILE.$$*" 0
 
-$CONFIGURATOR --extra-tests --autotools-style --var-file=$CONFIG_VAR_FILE.$$ --header-file=$CONFIG_HEADER.$$ --configurator-cc="$CONFIGURATOR_CC" --wrapper="$CONFIGURATOR_WRAPPER" "$CC" ${CWARNFLAGS-$BASE_WARNFLAGS} $CDEBUGFLAGS $COPTFLAGS $CSANFLAGS -I$CPATH -L$LIBRARY_PATH $SQLITE3_CFLAGS $SODIUM_CFLAGS $POSTGRES_INCLUDE <<EOF
+CONFIGURATOR_PATH_FLAGS=
+[ -z "$CPATH" ] || CONFIGURATOR_PATH_FLAGS="$CONFIGURATOR_PATH_FLAGS -I$CPATH"
+[ -z "$LIBRARY_PATH" ] || CONFIGURATOR_PATH_FLAGS="$CONFIGURATOR_PATH_FLAGS -L$LIBRARY_PATH"
+
+$CONFIGURATOR --extra-tests --autotools-style --var-file=$CONFIG_VAR_FILE.$$ --header-file=$CONFIG_HEADER.$$ --configurator-cc="$CONFIGURATOR_CC" --wrapper="$CONFIGURATOR_WRAPPER" "$CC" ${CWARNFLAGS-$BASE_WARNFLAGS} $CDEBUGFLAGS $COPTFLAGS $CSANFLAGS $CONFIGURATOR_PATH_FLAGS $SQLITE3_CFLAGS $SODIUM_CFLAGS $POSTGRES_INCLUDE <<EOF
 
 var=HAVE_ZLIB
 desc=zlib support
diff --git a/nix/shells.nix b/nix/shells.nix
index bb3588c28b3a..167100c4b47e 100644
--- a/nix/shells.nix
+++ b/nix/shells.nix
@@ -7,14 +7,48 @@
       system,
       ...
     }:
+    let
+      gsed = pkgs.writeShellScriptBin "gsed" ''
+        exec ${pkgs.gnused}/bin/sed "$@"
+      '';
+      libeatmydata = pkgs.libeatmydata.overrideAttrs (_: {
+        doCheck = false;
+        nativeCheckInputs = [ ];
+      });
+      devTools = [
+        libeatmydata
+        pkgs.shellcheck
+        pkgs.uv
+        gsed
+      ];
+      shellHook = ''
+        _cln_stop_regtest_on_exit() {
+          if command -v stop_ln >/dev/null 2>&1; then
+            stop_ln >/dev/null 2>&1 || true
+          fi
+        }
+
+        trap _cln_stop_regtest_on_exit EXIT
+      '';
+    in
     {
       devShells = {
-        default = pkgs.mkShell { inputsFrom = [ config.packages.default ]; };
-        postgres = pkgs.mkShell { inputsFrom = [ config.packages.cln-postgres ]; };
+        default = pkgs.mkShell {
+          inputsFrom = [ config.packages.default ];
+          packages = devTools;
+          inherit shellHook;
+        };
+        postgres = pkgs.mkShell {
+          inputsFrom = [ config.packages.cln-postgres ];
+          packages = devTools;
+          inherit shellHook;
+        };
         rust = pkgs.craneLib.devShell {
           checks = {
             inherit (self.checks.${system}) rust;
           };
+          packages = devTools;
+          inherit shellHook;
         };
       };
     };