diff --git a/src/w_wad.c b/src/w_wad.c
index 59e9a7210..2d717d12a 100644
--- a/src/w_wad.c
+++ b/src/w_wad.c
@@ -538,7 +538,7 @@ UINT16 W_LoadWadFile(const char *filename)
 					break;
 				default:
 					CONS_Alert(CONS_WARNING, "Lump has an unsupported compression type!\n");
-					lumpinfo[numlumps].compression = CM_NONE;
+					lumpinfo[numlumps].compression = CM_UNSUPPORTED;
 					break;
 				}
 				fseek(handle, eXFieldLen + eCommentLen, SEEK_CUR); // We skip to where we expect the next central directory entry or end marker to be.
@@ -1122,7 +1122,7 @@ size_t W_ReadLumpHeaderPwad(UINT16 wad, UINT16 lump, void *dest, size_t size, si
 			return size;
 		}
 	default:
-		return 0;
+		I_Error("wad %d, lump %d: unsupported compression type!", wad, lump);
 	}
 }
 
diff --git a/src/w_wad.h b/src/w_wad.h
index 1ddcd5a55..35d060279 100644
--- a/src/w_wad.h
+++ b/src/w_wad.h
@@ -35,7 +35,7 @@ typedef struct
 } wadinfo_t;
 
 // Available compression methods for lumps.
-enum compmethod{CM_NONE, CM_DEFLATE, CM_LZF};
+enum compmethod{CM_NONE, CM_DEFLATE, CM_LZF, CM_UNSUPPORTED};
 
 //  a memory entry of the wad directory
 typedef struct