diff --git a/.github/workflows/mingw-w64-steps.yml b/.github/workflows/mingw-w64-steps.yml
index c1eea06e5a6e..ca9dbd25392b 100644
--- a/.github/workflows/mingw-w64-steps.yml
+++ b/.github/workflows/mingw-w64-steps.yml
@@ -146,20 +146,17 @@ jobs:
       - name: Run compiler specs
         shell: msys2 {0}
         run: |
-          export CRYSTAL_SPEC_COMPILER_BIN="$(which crystal.exe)"
-          make compiler_spec
+          make compiler_spec CRYSTAL=.build/crystal
 
       - name: Run interpreter specs
         shell: msys2 {0}
         run: |
-          export CRYSTAL_SPEC_COMPILER_BIN="$(which crystal.exe)"
-          make interpreter_spec
+          make interpreter_spec CRYSTAL=.build/crystal
 
       - name: Run primitives specs
         shell: msys2 {0}
         run: |
-          export CRYSTAL_SPEC_COMPILER_BIN="$(which crystal.exe)"
-          make -o .build/crystal.exe primitives_spec # we know the compiler is fresh; do not rebuild it here
+          make -o .build/crystal.exe primitives_spec CRYSTAL=.build/crystal.exe # we know the compiler is fresh; do not rebuild it here
         env:
           SPEC_FLAGS: --tag=~external_commands # skip exec_external_command spec because it doesn't work with this setup
 
diff --git a/.github/workflows/win.yml b/.github/workflows/win.yml
index 7f4f40adc6a6..5474f0850beb 100644
--- a/.github/workflows/win.yml
+++ b/.github/workflows/win.yml
@@ -240,7 +240,7 @@ jobs:
 
       - name: Set up environment
         run: |
-          Add-Content $env:GITHUB_PATH "$(pwd)\build"
+          Add-Content $env:GITHUB_ENV "CRYSTAL=$(pwd)\build\crystal.exe"
           Add-Content $env:GITHUB_ENV "CRYSTAL_SPEC_COMPILER_BIN=$(pwd)\build\crystal.exe"
           Add-Content $env:GITHUB_ENV "LLVM_VERSION=${{ env.CI_LLVM_VERSION }}"
           Add-Content $env:GITHUB_ENV "LLVM_TARGETS=${{ env.CI_LLVM_TARGETS }}"
@@ -262,7 +262,7 @@ jobs:
         run: make -f Makefile.win cli_spec
 
       - name: Build samples
-        run: make -f Makefile.win samples
+        run: make -f Makefile.win -C samples
 
   test-std:
     runs-on: windows-2025-vs2026
@@ -295,8 +295,7 @@ jobs:
 
       - name: Set up environment
         run: |
-          Add-Content $env:GITHUB_PATH "$(pwd)\build"
-          Add-Content $env:GITHUB_ENV "CRYSTAL_SPEC_COMPILER_BIN=$(pwd)\build\crystal.exe"
+          Add-Content $env:GITHUB_ENV "CRYSTAL=$(pwd)\build\crystal.exe"
           Add-Content $env:GITHUB_ENV "LLVM_VERSION=${{ env.CI_LLVM_VERSION }}"
           Add-Content $env:GITHUB_ENV "LLVM_TARGETS=${{ env.CI_LLVM_TARGETS }}"
           Add-Content $env:GITHUB_ENV "LLVM_LDFLAGS=${{ env.CI_LLVM_LDFLAGS }}"
@@ -327,8 +326,7 @@ jobs:
 
       - name: Set up environment
         run: |
-          Add-Content $env:GITHUB_PATH "$(pwd)\build"
-          Add-Content $env:GITHUB_ENV "CRYSTAL_SPEC_COMPILER_BIN=$(pwd)\build\crystal.exe"
+          Add-Content $env:GITHUB_ENV "CRYSTAL=$(pwd)\build\crystal.exe"
           Add-Content $env:GITHUB_ENV "LLVM_VERSION=${{ env.CI_LLVM_VERSION }}"
           Add-Content $env:GITHUB_ENV "LLVM_TARGETS=${{ env.CI_LLVM_TARGETS }}"
           Add-Content $env:GITHUB_ENV "LLVM_LDFLAGS=${{ env.CI_LLVM_LDFLAGS }}"
diff --git a/Makefile b/Makefile
index c3bebf6ec3b1..e2beb3440667 100644
--- a/Makefile
+++ b/Makefile
@@ -285,7 +285,7 @@ $(O)/compiler_spec$(EXE): $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 
 $(O)/primitives_spec$(EXE): $(O)/$(CRYSTAL_BIN) $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	@mkdir -p $(O)
-	$(EXPORT_CC) ./bin/crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o $@ spec/primitives_spec.cr
+	$(EXPORT_CC) ./$(O)/crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o $@ spec/primitives_spec.cr
 
 $(O)/cli_spec$(EXE): $(O)/$(CRYSTAL_BIN) $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	@mkdir -p $(O)
diff --git a/Makefile.win b/Makefile.win
index bece8f7cc555..9c40fbd5da3c 100644
--- a/Makefile.win
+++ b/Makefile.win
@@ -223,7 +223,7 @@ $(O)\compiler_spec.exe: $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 
 $(O)\primitives_spec.exe: $(O)\crystal.exe $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	@$(call MKDIR,"$(O)")
-	.\bin\crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o "$@" spec\primitives_spec.cr
+	$(O)\crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o "$@" spec\primitives_spec.cr
 
 $(O)\cli_spec.exe: $(O)\crystal.exe $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	@$(call MKDIR,"$(O)")
diff --git a/bin/ci b/bin/ci
index 81426831ac94..35853022ceeb 100755
--- a/bin/ci
+++ b/bin/ci
@@ -106,28 +106,29 @@ build() {
   case $ARCH in
     i386)
       with_build_env 'make crystal threads=1'
-      with_build_env 'SPEC_SPLIT="0%4" make std_spec threads=1 junit_output=.junit/std_spec.0.xml'
-      with_build_env 'SPEC_SPLIT="1%4" make std_spec threads=1 junit_output=.junit/std_spec.1.xml'
-      with_build_env 'SPEC_SPLIT="2%4" make std_spec threads=1 junit_output=.junit/std_spec.2.xml'
-      with_build_env 'SPEC_SPLIT="3%4" make std_spec threads=1 junit_output=.junit/std_spec.3.xml'
+      with_build_env 'SPEC_SPLIT="0%4" make CRYSTAL=.build/crystal std_spec threads=1 junit_output=.junit/std_spec.0.xml'
+      with_build_env 'SPEC_SPLIT="1%4" make CRYSTAL=.build/crystal std_spec threads=1 junit_output=.junit/std_spec.1.xml'
+      with_build_env 'SPEC_SPLIT="2%4" make CRYSTAL=.build/crystal std_spec threads=1 junit_output=.junit/std_spec.2.xml'
+      with_build_env 'SPEC_SPLIT="3%4" make CRYSTAL=.build/crystal std_spec threads=1 junit_output=.junit/std_spec.3.xml'
 
       parts=16
       i=0
       while [ $i -lt $parts ]; do
-        with_build_env "CRYSTAL_SPEC_COMPILER_THREADS=1 SPEC_SPLIT=\"$i%$parts\" make compiler_spec threads=1 junit_output=.junit/compiler_spec.$i.xml"
+        with_build_env "CRYSTAL_SPEC_COMPILER_THREADS=1 SPEC_SPLIT=\"$i%$parts\" make CRYSTAL=.build/crystal compiler_spec threads=1 junit_output=.junit/compiler_spec.$i.xml"
         i=$((i + 1))
       done
 
-      with_build_env 'make primitives_spec threads=1 junit_output=.junit/primitives_spec.xml'
-      with_build_env 'make docs threads=1'
+      with_build_env 'make CRYSTAL=.build/crystal primitives_spec threads=1 junit_output=.junit/primitives_spec.xml'
+      with_build_env 'make CRYSTAL=.build/crystal docs threads=1'
       ;;
     *)
-      with_build_env 'make crystal primitives_spec std_spec compiler_spec docs threads=1 junit_output=.junit/spec.xml DOCS_OPTIONS="--json-config-url=/api/versions.json --canonical-base-url=https://crystal-lang.org/api/latest/"'
+      with_build_env 'make crystal'
+      with_build_env 'make CRYSTAL=.build/crystal primitives_spec std_spec compiler_spec docs threads=1 junit_output=.junit/spec.xml DOCS_OPTIONS="--json-config-url=/api/versions.json --canonical-base-url=https://crystal-lang.org/api/latest/"'
       ;;
   esac
 
-  with_build_env 'make samples'
-  with_build_env 'CRYSTAL_OPTS=--debug make samples'
+  with_build_env 'make -C samples CRYSTAL=../.build/crystal'
+  with_build_env 'CRYSTAL_OPTS=--debug make -C samples CRYSTAL=../.build/crystal'
 }
 
 format() {
diff --git a/bin/crystal b/bin/crystal
index 98d0903fdd0b..2dc229c1efc2 100755
--- a/bin/crystal
+++ b/bin/crystal
@@ -185,11 +185,6 @@ case "$(uname -s)" in
     ;;
 esac
 
-# CRYSTAL_EXEC_PATH determines the location of the `crystal` program for external
-# compiler commands.
-CRYSTAL_EXEC_PATH="$SCRIPT_ROOT"
-export CRYSTAL_EXEC_PATH
-
 if [ -x "$CRYSTAL_DIR/${CRYSTAL_BIN}" ]; then
   __warning_msg "Using compiled compiler at ${CRYSTAL_DIR#"$PWD/"}/${CRYSTAL_BIN}"
   exec "$CRYSTAL_DIR/${CRYSTAL_BIN}" "$@"
@@ -197,5 +192,10 @@ elif (! $PARENT_CRYSTAL_EXISTS); then
   __error_msg 'You need to have a crystal executable in your path! or set CRYSTAL env variable'
   exit 1
 else
+  # CRYSTAL_EXEC_PATH determines the location of the `crystal` program for external
+  # compiler commands.
+  CRYSTAL_EXEC_PATH="$SCRIPT_ROOT"
+  export CRYSTAL_EXEC_PATH
+
   exec "$PARENT_CRYSTAL" "$@"
 fi
diff --git a/spec/manual/find_executable_spec.cr b/spec/manual/find_executable_spec.cr
index 01bfd12f4d88..816e4c613df4 100644
--- a/spec/manual/find_executable_spec.cr
+++ b/spec/manual/find_executable_spec.cr
@@ -23,7 +23,7 @@ describe "Process.run" do
       src_fn = test_dir / "self_printer.cr"
       exe_fn = test_dir / "self_printer.exe"
       File.write(src_fn, "print #{name.inspect}")
-      Process.run(ENV["CRYSTAL_SPEC_COMPILER_BIN"]? || "bin/crystal", ["build", "-o", exe_fn.to_s, src_fn.to_s])
+      Process.run(ENV["CRYSTAL_SPEC_COMPILER_BIN"]? || File.join(".build", "crystal"), ["build", "-o", exe_fn.to_s, src_fn.to_s])
       Dir.mkdir_p((base_dir / name).parent)
       File.rename(exe_fn, base_dir / name)
     end
diff --git a/src/compiler/crystal/crystal_path.cr b/src/compiler/crystal/crystal_path.cr
index 2e10c9e567f8..f1a5e1ab050f 100644
--- a/src/compiler/crystal/crystal_path.cr
+++ b/src/compiler/crystal/crystal_path.cr
@@ -21,6 +21,8 @@ module Crystal
     def self.default_paths : Array(String)
       if path = ENV["CRYSTAL_PATH"]?
         path_array = path.split(Process::PATH_DELIMITER, remove_empty: true)
+      elsif dev_path = dev_path?
+        path_array = [DEFAULT_LIB_PATH, dev_path]
       elsif path = Crystal::Config.path.presence
         path_array = path.split(Process::PATH_DELIMITER, remove_empty: true)
         unless path_array.includes?(DEFAULT_LIB_PATH)
@@ -35,6 +37,16 @@ module Crystal
       path_array
     end
 
+    def self.dev_path? : String?
+      exe_path = Process.executable_path || return
+      dir_path = ::Path[exe_path].parent
+      return unless dir_path.basename == ".build"
+
+      src_path = dir_path.parent.join("src").to_s
+      return unless Dir.exists?(src_path)
+      src_path
+    end
+
     def self.default_path : String
       default_paths.join(Process::PATH_DELIMITER)
     end