diff --git a/src/newgrf_canal.cpp b/src/newgrf_canal.cpp
index c74bfd4d12..4a1278848d 100644
--- a/src/newgrf_canal.cpp
+++ b/src/newgrf_canal.cpp
@@ -56,7 +56,7 @@ static uint32 CanalGetVariable(const ResolverObject *object, byte variable, byte
 	DEBUG(grf, 1, "Unhandled canal property 0x%02X", variable);
 
 	*available = false;
-	return 0;
+	return UINT_MAX;
 }
 
 
diff --git a/src/newgrf_cargo.cpp b/src/newgrf_cargo.cpp
index 5e322a9ec0..b0f2620980 100644
--- a/src/newgrf_cargo.cpp
+++ b/src/newgrf_cargo.cpp
@@ -31,7 +31,7 @@ static uint32 CargoGetVariable(const ResolverObject *object, byte variable, byte
 	DEBUG(grf, 1, "Unhandled cargo property 0x%X", variable);
 
 	*available = false;
-	return 0;
+	return UINT_MAX;
 }
 
 
diff --git a/src/newgrf_generic.cpp b/src/newgrf_generic.cpp
index 465c75266d..6ce92b7afc 100644
--- a/src/newgrf_generic.cpp
+++ b/src/newgrf_generic.cpp
@@ -94,7 +94,7 @@ static uint32 GenericCallbackGetVariable(const ResolverObject *object, byte vari
 	DEBUG(grf, 1, "Unhandled generic feature property 0x%02X", variable);
 
 	*available = false;
-	return 0;
+	return UINT_MAX;
 }
 
 
diff --git a/src/newgrf_industries.cpp b/src/newgrf_industries.cpp
index 1121edeb52..e6f18a4453 100644
--- a/src/newgrf_industries.cpp
+++ b/src/newgrf_industries.cpp
@@ -380,7 +380,7 @@ uint32 IndustryGetVariable(const ResolverObject *object, byte variable, byte par
 	DEBUG(grf, 1, "Unhandled industry property 0x%X", variable);
 
 	*available = false;
-	return (uint32)-1;
+	return UINT_MAX;
 }
 
 static const SpriteGroup *IndustryResolveReal(const ResolverObject *object, const SpriteGroup *group)
diff --git a/src/newgrf_industrytiles.cpp b/src/newgrf_industrytiles.cpp
index 46d5eedf2e..ab35330b21 100644
--- a/src/newgrf_industrytiles.cpp
+++ b/src/newgrf_industrytiles.cpp
@@ -102,7 +102,7 @@ static uint32 IndustryTileGetVariable(const ResolverObject *object, byte variabl
 	DEBUG(grf, 1, "Unhandled industry tile property 0x%X", variable);
 
 	*available = false;
-	return (uint32)-1;
+	return UINT_MAX;
 }
 
 static const SpriteGroup *IndustryTileResolveReal(const ResolverObject *object, const SpriteGroup *group)
diff --git a/src/newgrf_town.cpp b/src/newgrf_town.cpp
index 4d24cce68e..084bf640c7 100644
--- a/src/newgrf_town.cpp
+++ b/src/newgrf_town.cpp
@@ -95,5 +95,5 @@ uint32 TownGetVariable(byte variable, byte parameter, bool *available, const Tow
 	DEBUG(grf, 1, "Unhandled town property 0x%X", variable);
 
 	*available = false;
-	return (uint32)-1;
+	return UINT_MAX;
 }