diff --git a/build_scripts/qt/compilers/clang.pri b/build_scripts/qt/compilers/clang.pri
index 0c16ae1..228ca95 100644
--- a/build_scripts/qt/compilers/clang.pri
+++ b/build_scripts/qt/compilers/clang.pri
@@ -8,4 +8,5 @@ QMAKE_CXXFLAGS += -Werror
 #All includes from the third-party directory will not warn.
 QMAKE_CXXFLAGS += --system-header-prefix=third-party
 
-QMAKE_CXXFLAGS += -Weffc++ -Wconversion
+# Sign conversion warns on auto generated Qt MOC files.
+QMAKE_CXXFLAGS += -Weffc++ -Wconversion -Wno-sign-conversion
diff --git a/build_scripts/qt/compilers/gcc.pri b/build_scripts/qt/compilers/gcc.pri
index 984ccdf..0da6167 100644
--- a/build_scripts/qt/compilers/gcc.pri
+++ b/build_scripts/qt/compilers/gcc.pri
@@ -10,4 +10,5 @@ QMAKE_CXXFLAGS += -Werror
 # GCC only switches
 QMAKE_CXXFLAGS += -Wduplicated-branches -Wduplicated-cond -Wlogical-op -Wrestrict -Wnull-dereference
 
-QMAKE_CXXFLAGS += -Wconversion
+# Sign conversion warns on auto generated Qt MOC files.
+QMAKE_CXXFLAGS += -Wconversion -Wno-sign-conversion