Bug: https://bugs.gentoo.org/610492
Upstream ticket: https://sourceforge.net/p/scourge/patches/3/

--- a/src/equip.cpp
+++ b/src/equip.cpp
@@ -595,7 +595,7 @@
 		}
 	}
 	if ( !found ) {
-		specialSkill = false;
+		specialSkill = NULL;
 		canvas->setTooltip( "" );
 	}
 	glDisable( GL_BLEND );
--- a/src/render/map.cpp
+++ b/src/render/map.cpp
@@ -3154,7 +3154,7 @@
 			if ( shape )
 				return shape;
 		}
-		return false;
+		return NULL;
 	}
 	if ( y1 == y2 ) {
 		if ( x1 > x2 ) SWAP( x1, x2 );
@@ -3163,7 +3163,7 @@
 			if ( shape )
 				return shape;
 		}
-		return false;
+		return NULL;
 	}