diff --git a/tools/libxl/libxlu_cfg_l.c b/tools/libxl/libxlu_cfg_l.c
index 7fedd41094..099aa8ef18 100644
--- a/tools/libxl/libxlu_cfg_l.c
+++ b/tools/libxl/libxlu_cfg_l.c
@@ -685,7 +685,7 @@ static int input (yyscan_t yyscanner );
 	if ( YY_CURRENT_BUFFER_LVALUE->yy_is_interactive ) \
 		{ \
 		int c = '*'; \
-		size_t n; \
+		int n; \
 		for ( n = 0; n < max_size && \
 			     (c = getc( yyin )) != EOF && c != '\n'; ++n ) \
 			buf[n] = (char) c; \
@@ -698,7 +698,7 @@ static int input (yyscan_t yyscanner );
 	else \
 		{ \
 		errno=0; \
-		while ( (result = fread(buf, 1, max_size, yyin))==0 && ferror(yyin)) \
+		while ( (result = fread(buf, 1, (yy_size_t) max_size, yyin)) == 0 && ferror(yyin)) \
 			{ \
 			if( errno != EINTR) \
 				{ \
diff --git a/tools/libxl/libxlu_disk_l.c b/tools/libxl/libxlu_disk_l.c
index 06f839e214..54160caa66 100644
--- a/tools/libxl/libxlu_disk_l.c
+++ b/tools/libxl/libxlu_disk_l.c
@@ -1158,7 +1158,7 @@ static int input (yyscan_t yyscanner );
 	if ( YY_CURRENT_BUFFER_LVALUE->yy_is_interactive ) \
 		{ \
 		int c = '*'; \
-		size_t n; \
+		int n; \
 		for ( n = 0; n < max_size && \
 			     (c = getc( yyin )) != EOF && c != '\n'; ++n ) \
 			buf[n] = (char) c; \
@@ -1171,7 +1171,7 @@ static int input (yyscan_t yyscanner );
 	else \
 		{ \
 		errno=0; \
-		while ( (result = fread(buf, 1, max_size, yyin))==0 && ferror(yyin)) \
+		while ( (result = fread(buf, 1, (yy_size_t) max_size, yyin)) == 0 && ferror(yyin)) \
 			{ \
 			if( errno != EINTR) \
 				{ \