diff --git a/Makefile b/Makefile
index b3e7dc51d0e5..51f234a22e7a 100644
--- a/Makefile
+++ b/Makefile
@@ -188,7 +188,7 @@ $(O)/std_spec: $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 $(O)/compiler_spec: $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	$(call check_llvm_config)
 	@mkdir -p $(O)
-	$(EXPORT_CC) $(EXPORTS) ./bin/crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o $@ spec/compiler_spec.cr
+	$(EXPORT_CC) $(EXPORTS) ./bin/crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o $@ spec/compiler_spec.cr --release
 
 $(O)/primitives_spec: $(O)/crystal $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	@mkdir -p $(O)
diff --git a/Makefile.win b/Makefile.win
index d8b97e512051..e3d8d0e7338e 100644
--- a/Makefile.win
+++ b/Makefile.win
@@ -179,7 +179,7 @@ $(O)\compiler_spec.exe: $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	$(call check_llvm_config)
 	@$(call MKDIR,"$(O)")
 	$(call export_vars)
-	.\bin\crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o "$@" spec\compiler_spec.cr
+	.\bin\crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o "$@" spec\compiler_spec.cr --release
 
 $(O)\primitives_spec.exe: $(O)\crystal.exe $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	@$(call MKDIR,"$(O)")