diff --git a/.travis.yml b/.travis.yml
index 5e50925c3..c90d4122e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -24,11 +24,11 @@ matrix:
             - lib32ncurses5-dev
             - g++-multilib
       env:
-        - CXXFLAGS="-g -m32" CFLAGS="-g -m32"
+          - CXXFLAGS="-g -O2 -m32" CFLAGS="-g -m32"
     - os: linux
       compiler: clang
       env:
-          - CXXFLAGS="-g -fno-omit-frame-pointer -fsanitize=address" ASAN_OPTIONS=check_initialization_order=1:detect_stack_use_after_return=1:detect_leaks=1
+          - CXXFLAGS="-g -O2 -fno-omit-frame-pointer -fsanitize=address" ASAN_OPTIONS=check_initialization_order=1:detect_stack_use_after_return=1:detect_leaks=1
       before_install: export CXX=clang++-3.8
       addons:
         apt:
@@ -49,7 +49,7 @@ matrix:
         - brew install pcre2 # use system PCRE2
         - brew outdated xctool || brew upgrade xctool # for xcode... soon.
       env:
-        - CXXFLAGS="-g -lstdc++"
+          - CXXFLAGS="-g -O2 -lstdc++"
   fast_finish: true
 
 script: