diff --git a/contrib/cross-aarch64.cmake b/contrib/cross-aarch64.cmake
index 8f36fc389c032fa58b2e5dbb84cbd444b4349141..c8d880d6391b5f384b802c098d63aefb6ba6e54c 100644
--- a/contrib/cross-aarch64.cmake
+++ b/contrib/cross-aarch64.cmake
@@ -26,8 +26,8 @@ set(CMAKE_CXX_COMPILER "aarch64-linux-gnu-g++")
 # optimizations with -O3.
 #
 if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
-	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
-	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE} -O2)
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE} -O2)
 endif()
 
 #-nostdlib
diff --git a/contrib/cross-arm-android-gnueabi.cmake b/contrib/cross-arm-android-gnueabi.cmake
index f0a18a54af53267a717577171989818e10ed1f84..da9aaae604c1f8731e40a3a9f20dab2a387d9689 100644
--- a/contrib/cross-arm-android-gnueabi.cmake
+++ b/contrib/cross-arm-android-gnueabi.cmake
@@ -30,8 +30,8 @@ set(CMAKE_CXX_COMPILER "${CROSS_PATH}/bin/arm-linux-androideabi-g++")
 # optimizations with -O3.
 #
 if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
-	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
-	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE} -O2)
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE} -O2)
 endif()
 
 # Where to look for the target environment. (More paths can be added here)
diff --git a/contrib/cross-arm-linux-gnueabihf.cmake b/contrib/cross-arm-linux-gnueabihf.cmake
index c7ceae9d595c3bec14155f96584606b3778d294c..289f27a5a72a5fc7bbf941b01ea919d1a0701820 100644
--- a/contrib/cross-arm-linux-gnueabihf.cmake
+++ b/contrib/cross-arm-linux-gnueabihf.cmake
@@ -27,8 +27,8 @@ set(CMAKE_CXX_COMPILER "${CROSS_PATH}/bin/arm-linux-gnueabihf-g++")
 # optimizations with -O3.
 #
 if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
-	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
-	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE} -O2)
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE} -O2)
 endif()
 
 # Where to look for the target environment. (More paths can be added here)
diff --git a/contrib/cross-esp32.cmake b/contrib/cross-esp32.cmake
index b99c37d65f508f7f98e5204200dce849739c7cef..2c8996b74ef93df9757636be2c9bcb53a4ad44fe 100644
--- a/contrib/cross-esp32.cmake
+++ b/contrib/cross-esp32.cmake
@@ -27,8 +27,8 @@ set(CMAKE_LINKER	"${CROSS_PATH}/bin/xtensa-esp32-elf-ld${EXECUTABLE_EXT}")
 # optimizations with -O3.
 #
 if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
-	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
-	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE} -O2)
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE} -O2)
 endif()
 
 SET(CMAKE_C_FLAGS "-nostdlib -Wall -Werror \
diff --git a/contrib/cross-ming.cmake b/contrib/cross-ming.cmake
index 5d737dcfb717db93b403798c6b0c8d80cfdebfc4..1b21014583615fe01a062f2bcd60b7239d330911 100644
--- a/contrib/cross-ming.cmake
+++ b/contrib/cross-ming.cmake
@@ -30,8 +30,8 @@ set(CMAKE_C_FLAGS "-Wno-error")
 # optimizations with -O3.
 #
 if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
-	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
-	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE} -O2)
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE} -O2)
 endif()
 
 # Where to look for the target environment. (More paths can be added here)
diff --git a/contrib/cross-w32.cmake b/contrib/cross-w32.cmake
index 0cb96cb3fe7e03baff7b5aad14325ee4ae0a346b..05128857bc342afb82c11371946d2028b1247c5f 100644
--- a/contrib/cross-w32.cmake
+++ b/contrib/cross-w32.cmake
@@ -29,8 +29,8 @@ set(CMAKE_C_FLAGS "-Wno-error")
 # optimizations with -O3.
 #
 if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
-	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
-	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE} -O2)
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE} -O2)
 endif()
 
 # Where to look for the target environment. (More paths can be added here)
diff --git a/contrib/cross-w64.cmake b/contrib/cross-w64.cmake
index 9d4a45ab683c067507fe1a59d40f29bc086fff10..4fff88256ce281775e02e4e7c54685729f534afa 100644
--- a/contrib/cross-w64.cmake
+++ b/contrib/cross-w64.cmake
@@ -29,8 +29,8 @@ set(CMAKE_C_FLAGS "-Wno-error")
 # optimizations with -O3.
 #
 if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
-	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
-	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE} -O2)
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE} -O2)
 endif()
 
 # Where to look for the target environment. (More paths can be added here)