diff --git a/src/Makefile b/src/Makefile
index a8a34f96..63bf1833 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -85,7 +85,7 @@ CXXFLAGS += -pedantic -std=c++2a -g -Wall -Wextra -Wno-unused-parameter -Wno-sig
 
 compiler := $(shell $(CXX) --version)
 ifneq (,$(findstring clang,$(compiler)))
-    CXXFLAGS += -frelaxed-template-template-args
+    CXXFLAGS += -frelaxed-template-template-args -Wno-ambiguous-reversed-operator
 else ifneq (,$(findstring g++,$(compiler)))
     CXXFLAGS += -Wno-init-list-lifetime
 endif
diff --git a/src/units.hh b/src/units.hh
index c7c9b8e6..ae025cb7 100644
--- a/src/units.hh
+++ b/src/units.hh
@@ -83,7 +83,7 @@ public:
     { m_value %= other.m_value; return static_cast<RealType&>(*this); }
 
     [[gnu::always_inline]]
-    constexpr friend auto operator==(RealType lhs, RealType rhs)
+    constexpr friend bool operator==(RealType lhs, RealType rhs)
     { return lhs.m_value == rhs.m_value; }
 
     [[gnu::always_inline]]