diff --git a/dumb/CMakeLists.txt b/dumb/CMakeLists.txt
index 97a72b42c9..c8fa34bf7b 100644
--- a/dumb/CMakeLists.txt
+++ b/dumb/CMakeLists.txt
@@ -14,6 +14,10 @@ if( ZD_CMAKE_COMPILER_IS_GNUC_COMPATIBLE )
 	endif(NOT CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR CMAKE_CXX_COMPILER_VERSION VERSION_GREATER "4.5")
 endif()
 
+if( MSVC )
+	set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /fp:fast" )
+endif()
+
 CHECK_FUNCTION_EXISTS( itoa ITOA_EXISTS )
 if( NOT ITOA_EXISTS )
 	add_definitions( -DNEED_ITOA=1 )
diff --git a/game-music-emu/CMakeLists.txt b/game-music-emu/CMakeLists.txt
index 27b065f42b..f1d467bcc0 100644
--- a/game-music-emu/CMakeLists.txt
+++ b/game-music-emu/CMakeLists.txt
@@ -29,6 +29,11 @@ if( ZD_CMAKE_COMPILER_IS_GNUCXX_COMPATIBLE )
 	endif()
 endif()
 
+if( MSVC )
+	set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /fp:fast" )
+	set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /fp:fast" )
+endif()
+
 
 # Default emulators to build (all of them! ;)
 if (NOT DEFINED USE_GME_AY)
diff --git a/gdtoa/CMakeLists.txt b/gdtoa/CMakeLists.txt
index e0a6bab297..94ab9a6914 100644
--- a/gdtoa/CMakeLists.txt
+++ b/gdtoa/CMakeLists.txt
@@ -5,7 +5,7 @@ set( CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -D_DEBUG" )
 # Disable warnings for << operator precedence (4554) and
 # unreferenced labels (4102) from VC
 if( MSVC )
-	set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /wd4554 /wd4102" )
+	set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /wd4554 /wd4102 /fp:fast" )
 endif()
 
 if( ZD_CMAKE_COMPILER_IS_GNUCXX_COMPATIBLE )
diff --git a/src/g_hexen/a_flechette.cpp b/src/g_hexen/a_flechette.cpp
index f26a6b41a1..7c8afb4cfc 100644
--- a/src/g_hexen/a_flechette.cpp
+++ b/src/g_hexen/a_flechette.cpp
@@ -332,7 +332,7 @@ int APoisonCloud::DoSpecialDamage (AActor *victim, int damage, FName damagetype)
 			int damage = 15 + (pr_poisoncloudd()&15);
 			if (mate)
 			{
-				damage = (int)((float)damage * level.teamdamage);
+				damage = (int)((double)damage * level.teamdamage);
 			}
 			// Handle passive damage modifiers (e.g. PowerProtection)
 			if (victim->Inventory != NULL)