diff --git a/src/win/Makefile.mingw b/src/win/Makefile.mingw
index e57efc9bd..381e446fb 100644
--- a/src/win/Makefile.mingw
+++ b/src/win/Makefile.mingw
@@ -320,7 +320,7 @@ else
  ifeq ($(OPTIM), y)
   AOPTIM	:= -mtune=native
   ifndef COPTIM
-   COPTIM	:= -O3 -flto=$(FLTO)
+   COPTIM	:= -O3 -ffp-contract=fast -flto=$(FLTO)
   endif
  else
   ifndef COPTIM
diff --git a/src/win/Makefile_ndr.mingw b/src/win/Makefile_ndr.mingw
index 1967963ea..e33767ad4 100644
--- a/src/win/Makefile_ndr.mingw
+++ b/src/win/Makefile_ndr.mingw
@@ -317,7 +317,7 @@ else
  ifeq ($(OPTIM), y)
   AOPTIM	:= -mtune=native
   ifndef COPTIM
-   COPTIM	:= -O3 -flto=$(FLTO)
+   COPTIM	:= -O3 -ffp-contract=fast -flto=$(FLTO)
   endif
  else
   ifndef COPTIM