diff --git a/CMakeLists.txt b/CMakeLists.txt
index 26fd972ae..2d358359c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,7 +6,8 @@ enable_testing()
 string(REGEX MATCH "clang" CMAKE_COMPILER_IS_CLANG "${CMAKE_C_COMPILER}")
 
 if(CMAKE_COMPILER_IS_GNUCC)
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O2 -Wall -Wextra -W -Wdeclaration-after-statement")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -W -Wdeclaration-after-statement")
+  set(CMAKE_C_FLAGS_RELEASE "-O2")
   set(CMAKE_C_FLAGS_DEBUG "-g3 -O0")
   set(CMAKE_C_FLAGS_COVERAGE "-g3 -O0 --coverage")
   set(CMAKE_C_FLAGS_ASAN "-fsanitize=address -fno-omit-frame-pointer -g3 -O1")
@@ -15,7 +16,8 @@ if(CMAKE_COMPILER_IS_GNUCC)
 endif(CMAKE_COMPILER_IS_GNUCC)
 
 if(CMAKE_COMPILER_IS_CLANG)
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O2 -Wall -Wextra -W -Wdeclaration-after-statement")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -W -Wdeclaration-after-statement")
+  set(CMAKE_C_FLAGS_RELEASE "-O2")
   set(CMAKE_C_FLAGS_DEBUG "-g3 -O0")
   set(CMAKE_C_FLAGS_COVERAGE "-g3 -O0 --coverage")
   set(CMAKE_C_FLAGS_ASAN "-fsanitize=address -fno-omit-frame-pointer -g3 -O1")