diff --git a/lib/src/german/CatGer.gf b/lib/src/german/CatGer.gf
index 88bd3d1b9..9a0087bb3 100644
--- a/lib/src/german/CatGer.gf
+++ b/lib/src/german/CatGer.gf
@@ -75,7 +75,7 @@ concrete CatGer of Cat =
 
     Conj = {s1,s2 : Str ; n : Number} ;
     Subj = {s : Str} ;
-    Prep = {s : Str ; c : PCase} ;
+    Prep = Preposition ;
 
 -- Open lexical classes, e.g. Lexicon
 
diff --git a/lib/src/german/MorphoGer.gf b/lib/src/german/MorphoGer.gf
index f064ef152..7c6e1143f 100644
--- a/lib/src/german/MorphoGer.gf
+++ b/lib/src/german/MorphoGer.gf
@@ -17,7 +17,7 @@ oper
 -- For $StructuralGer$.
 
   mkPrep : Str -> PCase -> Preposition = \s,c -> 
-    {s = s ; c = c} ;
+    {s = s ; c = c ; isPrep = True} ;
 
   nameNounPhrase : {s : Case => Str} ->  {s : PCase => Str ; a : Agr ; isPron : Bool} = \name -> heavyNP {
       s = \\c => usePrepC c (\k -> name.s ! k) ;
diff --git a/lib/src/german/ParadigmsGer.gf b/lib/src/german/ParadigmsGer.gf
index 14df916cb..d94ef4db3 100644
--- a/lib/src/german/ParadigmsGer.gf
+++ b/lib/src/german/ParadigmsGer.gf
@@ -351,7 +351,7 @@ mkV2 : overload {
 
 
   mmkN2  : N -> Prep -> N2 = \n,p -> n ** {c2 = p ; lock_N2 = <>} ;
-  vonN2 : N -> N2 = \n -> n ** {c2 = {s = "von" ; c = dative} ; lock_N2 = <>} ;
+  vonN2 : N -> N2 = \n -> n ** {c2 = von_Prep ; lock_N2 = <>} ;
 
   mkN3 = \n,p,q -> n ** {c2 = p ; c3 = q ; lock_N3 = <>} ;
 
@@ -397,10 +397,10 @@ mkV2 : overload {
 
   mkAdv s = {s = s ; lock_Adv = <>} ;
 
-  mkPrep s c = {s = s ; c = c ; lock_Prep = <>} ;
-  accPrep = mkPrep [] accusative ;
-  datPrep = mkPrep [] dative ;
-  genPrep = mkPrep [] genitive ;
+  mkPrep s c = {s = s ; c = c ; isPrep = True ; lock_Prep = <>} ;
+  accPrep = {s = [] ; c = accusative ; isPrep = False ; lock_Prep = <>} ;
+  datPrep = {s = [] ; c = dative ; isPrep = False ; lock_Prep = <>} ;
+  genPrep = {s = [] ; c = genitive ; isPrep = False ; lock_Prep = <>} ;
   --von_Prep = mkPrep "von" dative ;
   von_Prep = mkPrep [] vonDat_Case ;
   zu_Prep = mkPrep [] zuDat_Case ;
@@ -472,8 +472,8 @@ mkV2 : overload {
   werden_V = MorphoGer.werden_V ** {lock_V = <>} ;
 
   prepV2 v c   = v ** {c2 = c ; lock_V2 = <>} ;
-  dirV2 v = prepV2 v (mkPrep [] accusative) ;
-  datV2 v = prepV2 v (mkPrep [] dative) ;
+  dirV2 v = prepV2 v accPrep ;
+  datV2 v = prepV2 v datPrep ;
 
   mkV3 v c d = v ** {c2 = c ; c3 = d ; lock_V3 = <>} ;
   dirV3 v p = mkV3 v (mkPrep [] accusative) p ;
diff --git a/lib/src/german/ResGer.gf b/lib/src/german/ResGer.gf
index 62eacd21d..abac3e8d2 100644
--- a/lib/src/german/ResGer.gf
+++ b/lib/src/german/ResGer.gf
@@ -344,7 +344,7 @@ resource ResGer = ParamX ** open Prelude in {
 
 -- Prepositions for complements indicate the complement case.
 
-  Preposition : Type = {s : Str ; c : PCase} ;
+  Preposition : Type = {s : Str ; c : PCase ; isPrep : Bool} ;
 
 -- To apply a preposition to a complement.
 
@@ -354,7 +354,7 @@ resource ResGer = ParamX ** open Prelude in {
 -- To build a preposition from just a case.
 
   noPreposition : Case -> Preposition = \c -> 
-    {s = [] ; c = NPC c} ;
+    {s = [] ; c = NPC c ; isPrep = False} ;
 
 -- Pronouns and articles
 -- Here we define personal and relative pronouns.
@@ -608,9 +608,9 @@ resource ResGer = ParamX ** open Prelude in {
 
   isLightComplement : Bool -> Preposition -> Bool = \isPron,prep -> case isPron of {
      False => False ;
-     _ => case prep.c of {
-       NPC Acc => True ;
-       _ => False
+     _ => case prep.isPrep of {
+       True => False ;
+       _ => True
        }
      } ;