diff --git a/ReC98.h b/ReC98.h
index a83782f6..f8b46504 100644
--- a/ReC98.h
+++ b/ReC98.h
@@ -79,29 +79,38 @@ typedef void ( far pascal * far   farfunc_t_far)(void);
 
 // PC-98 VRAM planes
 // -----------------
+// Planar 1bpp types, describing horizontal lines of 8, 16, or 32 pixels.
+typedef uint8_t planar8_t;
+typedef uint16_t planar16_t;
+typedef uint32_t planar32_t;
+// ... and the same for the rare cases where ZUN's code used signed types.
+typedef int8_t splanar8_t;
+typedef int16_t splanar16_t;
+typedef int32_t splanar32_t;
+
 typedef enum {
 	PL_B, PL_R, PL_G, PL_E, PL_COUNT
 } vram_plane_t;
 
 typedef struct {
-	char B, R, G, E;
+	planar8_t B, R, G, E;
 } vram_planar_8_pixels_t;
 
 typedef struct {
-	int B, R, G, E;
+	planar16_t B, R, G, E;
 } vram_planar_16_pixels_t;
 
 // Since array subscripts create slightly different assembly in places, we
 // offer both variants.
-extern char *VRAM_PLANE[PL_COUNT];
-extern char *VRAM_PLANE_B;
-extern char *VRAM_PLANE_G;
-extern char *VRAM_PLANE_R;
-extern char *VRAM_PLANE_E;
+extern planar8_t *VRAM_PLANE[PL_COUNT];
+extern planar8_t *VRAM_PLANE_B;
+extern planar8_t *VRAM_PLANE_G;
+extern planar8_t *VRAM_PLANE_R;
+extern planar8_t *VRAM_PLANE_E;
 
 #define PLANE_DWORD_BLIT(dst, src) \
-	for(p = 0; p < PLANE_SIZE; p += 4) { \
-		*(long*)((dst) + p) = *(long*)((src) + p); \
+	for(p = 0; p < PLANE_SIZE; p += (int)sizeof(planar32_t)) { \
+		*(planar32_t*)((dst) + p) = *(planar32_t*)((src) + p); \
 	}
 
 #define VRAM_OFFSET(x, y) ((x) >> 3) + (y << 6) + (y << 4)
diff --git a/th01/grps2xsc.c b/th01/grps2xsc.c
index aa74ac90..fa9329e1 100644
--- a/th01/grps2xsc.c
+++ b/th01/grps2xsc.c
@@ -1,8 +1,8 @@
-void scale_2x(unsigned long *dst32, int src16)
+void scale_2x(planar32_t *dst32, splanar16_t src16)
 {
-	unsigned long mask = 1;
-	unsigned long srcex = 0;
-	unsigned long dst_local;
+	planar32_t mask = 1;
+	planar32_t srcex = 0;
+	planar32_t dst_local;
 	int i;
 
 	srcex = src16;
@@ -24,7 +24,7 @@ void graph_slow_2xscale_rect_1_to_0(int x0, int y0, int x1, int y1, int w1, int
 	int col16;
 	int row;
 	vram_planar_16_pixels_t px16;
-	int px16_nonzero;
+	planar16_t px16_nonzero;
 
 	for(row = 0; row < h1; row++) {
 		int p0 = row_p0;
@@ -32,32 +32,32 @@ void graph_slow_2xscale_rect_1_to_0(int x0, int y0, int x1, int y1, int w1, int
 		for(col16 = 0; col16 < w1 / 16; col16++) {
 			int scale_p;
 			graph_accesspage(1);
-			px16.B = *(int*)(VRAM_PLANE_B + p1);
-			px16.R = *(int*)(VRAM_PLANE_R + p1);
-			px16.G = *(int*)(VRAM_PLANE_G + p1);
-			px16.E = *(int*)(VRAM_PLANE_E + p1);
+			px16.B = *(planar16_t*)(VRAM_PLANE_B + p1);
+			px16.R = *(planar16_t*)(VRAM_PLANE_R + p1);
+			px16.G = *(planar16_t*)(VRAM_PLANE_G + p1);
+			px16.E = *(planar16_t*)(VRAM_PLANE_E + p1);
 			px16_nonzero = px16.B | px16.R | px16.G | px16.E;
 			for(scale_p = 0; scale_p < ROW_SIZE * 2; scale_p += ROW_SIZE) {
-				unsigned long dst32;
-				unsigned long px32_nonzero;
+				planar32_t dst32;
+				planar32_t px32_nonzero;
 
 				graph_accesspage(0);
 				scale_2x(&px32_nonzero, px16_nonzero);
 				grcg_setcolor_rmw(0);
-				*(long*)(VRAM_PLANE_B + p0 + scale_p) = px32_nonzero;
+				*(planar32_t*)(VRAM_PLANE_B + p0 + scale_p) = px32_nonzero;
 				grcg_off();
 
 				scale_2x(&dst32, px16.B);
-				*(long*)(VRAM_PLANE_B + p0 + scale_p) |= dst32;
+				*(planar32_t*)(VRAM_PLANE_B + p0 + scale_p) |= dst32;
 
 				scale_2x(&dst32, px16.R);
-				*(long*)(VRAM_PLANE_R + p0 + scale_p) |= dst32;
+				*(planar32_t*)(VRAM_PLANE_R + p0 + scale_p) |= dst32;
 
 				scale_2x(&dst32, px16.G);
-				*(long*)(VRAM_PLANE_G + p0 + scale_p) |= dst32;
+				*(planar32_t*)(VRAM_PLANE_G + p0 + scale_p) |= dst32;
 
 				scale_2x(&dst32, px16.E);
-				*(long*)(VRAM_PLANE_E + p0 + scale_p) |= dst32;
+				*(planar32_t*)(VRAM_PLANE_E + p0 + scale_p) |= dst32;
 			}
 			p1 += 2;
 			p0 += 4;
diff --git a/th01/hardware/egccopyr.c b/th01/hardware/egccopyr.c
index 1ff6f897..e5269ba4 100644
--- a/th01/hardware/egccopyr.c
+++ b/th01/hardware/egccopyr.c
@@ -24,7 +24,7 @@ void egc_copy_rect_1_to_0(int x, int y, int w, int h)
 	int row;
 	int col;
 	int row_p;
-	int bits;
+	planar16_t bits;
 	int p;
 
 	x_end += w;
@@ -33,8 +33,8 @@ void egc_copy_rect_1_to_0(int x, int y, int w, int h)
 	egc_start_copy();
 	for(row = 0; row < h; row++) {
 		for(col = x_floor, p = row_p; col < x_end; p += 2, col += 16) {
-			graph_accesspage(1); bits = *(int*)(VRAM_PLANE_B + p);
-			graph_accesspage(0); *(int*)(VRAM_PLANE_B + p) = bits;
+			graph_accesspage(1); bits = *(planar16_t*)(VRAM_PLANE_B + p);
+			graph_accesspage(0); *(planar16_t*)(VRAM_PLANE_B + p) = bits;
 		}
 		row_p += 640 / 8;
 	}
diff --git a/th02/hardware/grppsafx.c b/th02/hardware/grppsafx.c
index 2116d496..6919734b 100644
--- a/th02/hardware/grppsafx.c
+++ b/th02/hardware/grppsafx.c
@@ -4,15 +4,15 @@
 void graph_putsa_fx(int x, int y, int fx, const unsigned char *str)
 {
 	uint16_t codepoint;
-	unsigned int glyph_row;
+	planar16_t glyph_row;
 	unsigned char far *vram;
 	int fullwidth;
 	int first_bit;
 	int weight = (fx >> 4) & 3;
 	int spacing = (fx >> 6) & 7;
 	int line;
-	unsigned int glyph[GLYPH_HEIGHT];
-	register unsigned int glyph_row_orig;
+	planar16_t glyph[GLYPH_HEIGHT];
+	register planar16_t glyph_row_orig;
 
 	grcg_setcolor(GC_RMW, fx);
 	OUTB(0x68, 0xB); // CG ROM dot access
diff --git a/th02/op_02_1.c b/th02/op_02_1.c
index d9a70477..93f9a859 100644
--- a/th02/op_02_1.c
+++ b/th02/op_02_1.c
@@ -26,15 +26,15 @@ void pascal graph_copy_rect_1_to_0(int x, int y, int w, int h)
 			if(row_p >= 0) {
 				vram_planar_16_pixels_t p16;
 				graph_accesspage(1);
-				p16.B = *(int*)(VRAM_PLANE_B + p);
-				p16.R = *(int*)(VRAM_PLANE_R + p);
-				p16.G = *(int*)(VRAM_PLANE_G + p);
-				p16.E = *(int*)(VRAM_PLANE_E + p);
+				p16.B = *(planar16_t*)(VRAM_PLANE_B + p);
+				p16.R = *(planar16_t*)(VRAM_PLANE_R + p);
+				p16.G = *(planar16_t*)(VRAM_PLANE_G + p);
+				p16.E = *(planar16_t*)(VRAM_PLANE_E + p);
 				graph_accesspage(0);
-				*(int*)(VRAM_PLANE_B + p) = p16.B;
-				*(int*)(VRAM_PLANE_R + p) = p16.R;
-				*(int*)(VRAM_PLANE_G + p) = p16.G;
-				*(int*)(VRAM_PLANE_E + p) = p16.E;
+				*(planar16_t*)(VRAM_PLANE_B + p) = p16.B;
+				*(planar16_t*)(VRAM_PLANE_R + p) = p16.R;
+				*(planar16_t*)(VRAM_PLANE_G + p) = p16.G;
+				*(planar16_t*)(VRAM_PLANE_E + p) = p16.E;
 			}
 		}
 		row_p += ROW_SIZE;
diff --git a/th02/op_05.c b/th02/op_05.c
index 4e8aeb38..f9081c4f 100644
--- a/th02/op_05.c
+++ b/th02/op_05.c
@@ -68,7 +68,7 @@ void darken_pic_at(int x, int y)
 	grcg_setcolor(GC_RMW, 0);
 	for(row = 0; row < 144; row++, row_p += 640 / 8)  {
 		for(col = 0; col < 192 / 8; col += 2) {
-			*(int*)(VRAM_PLANE_B + row_p + col) =
+			*(planar16_t*)(VRAM_PLANE_B + row_p + col) =
 				row & 1 ? 0xAAAA : 0x5555
 			;
 		}
diff --git a/th05/music/piano.h b/th05/music/piano.h
index 1ec3ddce..95c3ff57 100644
--- a/th05/music/piano.h
+++ b/th05/music/piano.h
@@ -16,7 +16,7 @@
 #define PIANO_VRAM_W ((PIANO_OCTAVES * PIANO_OCTAVE_W) / 8)
 
 // Sprite data
-extern const unsigned char PIANO_KEYS_BLACK[PIANO_VRAM_W];
+extern const planar8_t PIANO_KEYS_BLACK[PIANO_VRAM_W];
 /// --------
 
 // Using the same naming convention as for the gaiji characters...
@@ -38,7 +38,7 @@ typedef enum {
 #define PIANO_LABEL_FONT_W 8
 #define PIANO_LABEL_FONT_H 8
 
-extern const unsigned char PIANO_LABEL_FONT[pl_COUNT][PIANO_LABEL_FONT_H];
+extern const planar8_t PIANO_LABEL_FONT[pl_COUNT][PIANO_LABEL_FONT_H];
 
 #define PIANO_LABEL_DIST_X 32
 #define PIANO_LABEL_DIST_Y 4