diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index 887874f4b49fa9ac900042fed96aae42467552b7..d2b5adf46512f20feb7fc27a14d39bc37c10e3e4 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -216,9 +216,9 @@ static inline char *__get_heap(size_t s, size_t a, size_t n)
 #define GET_HEAP(type, n) \
 	((type *)__get_heap(sizeof(type),__alignof__(type),(n)))
 
-static inline int heap_free(void)
+static inline bool heap_free(size_t n)
 {
-	return heap_end-HEAP;
+	return (int)(heap_end-HEAP) >= (int)n;
 }
 
 /* copy.S */
diff --git a/arch/x86/boot/video-bios.c b/arch/x86/boot/video-bios.c
index 68e65d95cdfd8627a69df2ed1ec7cf33cd392ca4..ed0672a818709b86d8c6ebd6416269434934091e 100644
--- a/arch/x86/boot/video-bios.c
+++ b/arch/x86/boot/video-bios.c
@@ -79,7 +79,7 @@ static int bios_probe(void)
 	video_bios.modes = GET_HEAP(struct mode_info, 0);
 
 	for (mode = 0x14; mode <= 0x7f; mode++) {
-		if (heap_free() < sizeof(struct mode_info))
+		if (!heap_free(sizeof(struct mode_info)))
 			break;
 
 		if (mode_defined(VIDEO_FIRST_BIOS+mode))
diff --git a/arch/x86/boot/video-vesa.c b/arch/x86/boot/video-vesa.c
index 19219071071023e631518e102c4dbcc7481dea17..4716b9a963575aa8d0eedf703feaa7997ada608e 100644
--- a/arch/x86/boot/video-vesa.c
+++ b/arch/x86/boot/video-vesa.c
@@ -57,7 +57,7 @@ static int vesa_probe(void)
 	while ((mode = rdfs16(mode_ptr)) != 0xffff) {
 		mode_ptr += 2;
 
-		if (heap_free() < sizeof(struct mode_info))
+		if (!heap_free(sizeof(struct mode_info)))
 			break;	/* Heap full, can't save mode info */
 
 		if (mode & ~0x1ff)
diff --git a/arch/x86/boot/video.c b/arch/x86/boot/video.c
index e4ba897bf9a3748c89e442141887ea9e0dbba721..ad9712f01739748c0d0d7d727ac34e20401de26f 100644
--- a/arch/x86/boot/video.c
+++ b/arch/x86/boot/video.c
@@ -371,7 +371,7 @@ static void save_screen(void)
 	saved.curx = boot_params.screen_info.orig_x;
 	saved.cury = boot_params.screen_info.orig_y;
 
-	if (heap_free() < saved.x*saved.y*sizeof(u16)+512)
+	if (!heap_free(saved.x*saved.y*sizeof(u16)+512))
 		return;		/* Not enough heap to save the screen */
 
 	saved.data = GET_HEAP(u16, saved.x*saved.y);