diff --git a/src/windows/clear_scenery.c b/src/windows/clear_scenery.c
index 7b3fb34120..819340bc07 100644
--- a/src/windows/clear_scenery.c
+++ b/src/windows/clear_scenery.c
@@ -27,7 +27,7 @@
 #include "../interface/window.h"
 #include "../interface/themes.h"
 
-#define MINIMUM_TOOL_SIZE 0
+#define MINIMUM_TOOL_SIZE 1
 #define MAXIMUM_TOOL_SIZE 64
 
 enum WINDOW_CLEAR_SCENERY_WIDGET_IDX {
diff --git a/src/windows/land_rights.c b/src/windows/land_rights.c
index 6b6b533045..ce0ea3cf89 100644
--- a/src/windows/land_rights.c
+++ b/src/windows/land_rights.c
@@ -29,7 +29,7 @@
 #include "../game.h"
 #include "../interface/themes.h"
 
-#define MINIMUM_TOOL_SIZE 0
+#define MINIMUM_TOOL_SIZE 1
 #define MAXIMUM_TOOL_SIZE 64
 
 enum WINDOW_WATER_WIDGET_IDX {
diff --git a/src/windows/water.c b/src/windows/water.c
index cbe2803606..ea3de071c3 100644
--- a/src/windows/water.c
+++ b/src/windows/water.c
@@ -27,7 +27,7 @@
 #include "../world/map.h"
 #include "../interface/themes.h"
 
-#define MINIMUM_TOOL_SIZE 0
+#define MINIMUM_TOOL_SIZE 1
 #define MAXIMUM_TOOL_SIZE 64
 
 enum WINDOW_WATER_WIDGET_IDX {