diff --git a/error.c b/error.c
index 64de2c5..31197bf 100644
--- a/error.c
+++ b/error.c
@@ -364,7 +364,7 @@ static char *ErrorFileName(void)
 	}
 	else
 	{
-		strcat(errFileName, DIRECTORY_DELIMITER ERROR_FILE_NAME);
+		strcat(errFileName, ERROR_FILE_NAME);
 	}
 	return errFileName;
 }
diff --git a/misc.c b/misc.c
index 94b9b7e..db4f84e 100644
--- a/misc.c
+++ b/misc.c
@@ -279,8 +279,7 @@ void MS_SuggestFileExt(char *base, char *extension)
 	char *search;
 
 	search = base+strlen(base)-1;
-	while(*search != ASCII_SLASH && *search != ASCII_BACKSLASH
-		&& search != base)
+	while(!MS_IsDirectoryDelimiter(*search) && search != base)
 	{
 		if(*search-- == '.')
 		{
@@ -290,6 +289,22 @@ void MS_SuggestFileExt(char *base, char *extension)
 	strcat(base, extension);
 }
 
+//==========================================================================
+//
+// MS_IsDirectoryDelimiter
+//
+//==========================================================================
+
+boolean MS_IsDirectoryDelimiter(char foo)
+{
+#if defined(_WIN32) || defined(__MSDOS__)
+	return foo == '/' || foo == '\\' || foo == ':';
+#else
+	return foo == '/';
+#endif
+}
+
+
 //==========================================================================
 //
 // MS_StripFileExt
@@ -301,8 +316,7 @@ void MS_StripFileExt(char *name)
 	char *search;
 
 	search = name+strlen(name)-1;
-	while(*search != ASCII_SLASH && *search != ASCII_BACKSLASH
-		&& search != name)
+	while(!MS_IsDirectoryDelimiter(*search) && search != name)
 	{
 		if(*search == '.')
 		{
@@ -317,6 +331,8 @@ void MS_StripFileExt(char *name)
 //
 // MS_StripFilename
 //
+// [RH] This now leaves the directory delimiter in place.
+//
 //==========================================================================
 
 boolean MS_StripFilename(char *name)
@@ -330,8 +346,8 @@ boolean MS_StripFilename(char *name)
 		{ // No directory delimiter
 			return NO;
 		}
-	} while(*c != DIRECTORY_DELIMITER_CHAR);
-	*c = 0;
+	} while(!MS_IsDirectoryDelimiter(*c));
+	*(c+1) = 0;
 	return YES;
 }
 
@@ -380,15 +396,13 @@ void MS_Message(msg_t type, char *text, ...)
 
 boolean MS_IsPathAbsolute(char *name)
 {
-#ifdef WIN32
-	// In windows, the second character must be : if it is an
+#if defined(_WIN32) || defined(__MSDOS__)
+	// In Windows, the second character must be : if it is an
 	// absolute path (the first character indicates the drive)
-	if(name[0] != '\0')
-		return (name[1] == ':') ? TRUE : FALSE;
-	else
-		return FALSE;
-#else
-	// In linux, the first character must be / for a root path
-	return (name[0] == '/') ? TRUE : FALSE;
+	// or the first character is either / or \ for absolute path
+	if((name[0] != '\0') && (name[1] == ':'))
+		return TRUE;
 #endif
+	// In Unix-land, the first character must be / for a root path
+	return MS_IsDirectoryDelimiter(name[0]);
 }
diff --git a/misc.h b/misc.h
index 9234db0..4e57baf 100644
--- a/misc.h
+++ b/misc.h
@@ -15,9 +15,6 @@
 
 // MACROS ------------------------------------------------------------------
 
-#define ASCII_SLASH 47
-#define ASCII_BACKSLASH 92
-
 // TYPES -------------------------------------------------------------------
 
 typedef enum
@@ -45,6 +42,7 @@ void MS_StripFileExt(char *name);
 boolean MS_StripFilename(char *path);
 void MS_Message(msg_t type, char *text, ...);
 boolean MS_IsPathAbsolute(char *name);
+boolean MS_IsDirectoryDelimiter(char test);
 
 // PUBLIC DATA DECLARATIONS ------------------------------------------------
 
diff --git a/token.c b/token.c
index 1c2ae41..bc19cc9 100644
--- a/token.c
+++ b/token.c
@@ -320,10 +320,10 @@ void TK_AddIncludePath(char *sourcePath)
 		strcpy(IncludePaths[NumIncludePaths], sourcePath);
 		
 		// Not ending with directory delimiter?
-		if(*(IncludePaths[NumIncludePaths] + strlen(IncludePaths[NumIncludePaths]) - 1) != DIRECTORY_DELIMITER_CHAR)
+		if(!MS_IsDirectoryDelimiter(*(IncludePaths[NumIncludePaths] + strlen(IncludePaths[NumIncludePaths]) - 1)))
 		{
 			// Add a directory delimiter to the include path
-			strcat(IncludePaths[NumIncludePaths], DIRECTORY_DELIMITER);
+			strcat(IncludePaths[NumIncludePaths], "/");
 		}
 		NumIncludePaths++;
 	}
@@ -346,11 +346,6 @@ static void SetLocalIncludePath(char *sourceName)
 	{
 		IncludePaths[0][0] = 0;
 	}
-	else
-	{
-		// Add a directory delimiter to the include path
-		strcat(IncludePaths[0], DIRECTORY_DELIMITER);
-	}
 }
 
 
@@ -386,7 +381,24 @@ void TK_Include(char *fileName)
 	// Handle absolute paths
 	if(MS_IsPathAbsolute(fileName))
 	{
+#if defined(_WIN32) || defined(__MSDOS__)
+		sourceName[0] = '\0';
+		if(MS_IsDirectoryDelimiter(fileName[0]))
+		{
+			// The source file is absolute for the drive, but does not
+			// specify a drive. Use the path for the current file to
+			// get the drive letter, if it has one.
+			if(IncludePaths[0][0] != '\0' && IncludePaths[0][1] == ':')
+			{
+				sourceName[0] = IncludePaths[0][0];
+				sourceName[1] = ':';
+				sourceName[2] = '\0';
+			}
+		}
+		strcat(sourceName, fileName);
+#else
 		strcpy(sourceName, fileName);
+#endif
 		foundfile = MS_FileExists(sourceName);
 	}
 	else
@@ -410,7 +422,9 @@ void TK_Include(char *fileName)
 		ERR_ErrorAt(tk_SourceName, tk_Line);
 		ERR_Exit(ERR_CANT_FIND_INCLUDE, YES, fileName, tk_SourceName, tk_Line);
 	}
-	
+
+	MS_Message(MSG_DEBUG, "*Include file found at %s\n", sourceName);
+
 	// Now change the first include path to the file directory
 	SetLocalIncludePath(sourceName);
 	
@@ -1018,8 +1032,8 @@ static void ProcessQuoteToken(void)
 			*text++ = Chr;
 		}
 		// escape the character after a backslash [JB]
-		if(Chr == ASCII_BACKSLASH)
-			escaped ^= (Chr == ASCII_BACKSLASH);
+		if(Chr == '\\')
+			escaped ^= (Chr == '\\');
 		else
 			escaped = FALSE;
 		NextChr();