diff --git a/Pm/PmCompilerOptions.icl b/Pm/PmCompilerOptions.icl
index 2b38c256263a2728ed05328b045702ef7b8a33fd..f54f2aa6d263d455253c8cd27ca68ff3d545f307 100644
--- a/Pm/PmCompilerOptions.icl
+++ b/Pm/PmCompilerOptions.icl
@@ -22,7 +22,7 @@ UnexpectedReport message
 
 instance == ListTypes
 where
-	(==) :: ListTypes ListTypes -> Bool
+	(==) :: !ListTypes !ListTypes -> Bool
 	(==) NoTypes NoTypes
 		=	True
 	(==) InferredTypes InferredTypes
@@ -48,7 +48,7 @@ where
 
 instance fromString ListTypes
 where
-	fromString :: {#Char} -> ListTypes
+	fromString :: !{#Char} -> ListTypes
 	fromString "NoTypes"
 		=	NoTypes
 	fromString "InferredTypes"
diff --git a/Pm/PmTypes.icl b/Pm/PmTypes.icl
index 64aca54b88ce7688b59e328eee96f7173e00bc67..e857f479e4acd0885bd7e4e05d9028d86ae0ab7e 100644
--- a/Pm/PmTypes.icl
+++ b/Pm/PmTypes.icl
@@ -62,7 +62,7 @@ ProcessorSuffix I386				= ".o"
 
 instance == Processor
 where
-	(==) :: Processor Processor -> Bool
+	(==) :: !Processor !Processor -> Bool
 	(==) CurrentProcessor CurrentProcessor		=	True
 	(==) MC68000 MC68000						=	True
 	(==) MC68020 MC68020						=	True
@@ -75,7 +75,7 @@ where
 
 instance fromString Processor
 where
-	fromString :: {#Char} -> Processor
+	fromString :: !{#Char} -> Processor
 	fromString "CurrentProcessor"		=	CurrentProcessor
 	fromString "MC68000"				=	MC68000
 	fromString "MC68020"				=	MC68020
@@ -88,7 +88,7 @@ where
 
 instance toString Processor
 where
-	toString :: Processor -> {#Char}
+	toString :: !Processor -> {#Char}
 	toString MC68000				=	"MC68000"
 	toString MC68020				=	"MC68020"
 	toString MC68020_and_68881		=	"MC68020_and_68881"
@@ -345,7 +345,7 @@ DefApplicationOptions =
 
 instance == Output
 where
-	(==) :: Output Output -> Bool
+	(==) :: !Output !Output -> Bool
 	(==) BasicValuesOnly BasicValuesOnly
 		=	True
 	(==) ShowConstructors ShowConstructors
@@ -359,7 +359,7 @@ where
 
 instance fromString Output
 where
-	fromString :: {#Char} -> Output
+	fromString :: !{#Char} -> Output
 	fromString "BasicValuesOnly"
 		=	BasicValuesOnly
 	fromString "ShowConstructors"
@@ -373,7 +373,7 @@ where
 
 instance toString Output
 where
-	toString :: Output -> {#Char}
+	toString :: !Output -> {#Char}
 	toString BasicValuesOnly
 		=	"BasicValuesOnly"
 	toString ShowConstructors