diff --git a/cucul/canvas.c b/cucul/canvas.c
index 9f9ff71..7905331 100644
--- a/cucul/canvas.c
+++ b/cucul/canvas.c
@@ -274,9 +274,6 @@ int cucul_clear_canvas(cucul_canvas_t *cv)
  *  - \c EINVAL A mask was specified but the mask size and source canvas
  *    size do not match.
  *
- *  FIXME: this function may corrupt the canvas if fullwidth characters
- *         appear at odd places.
- *
  *  \param dst The destination canvas.
  *  \param x X coordinate.
  *  \param y Y coordinate.
@@ -308,28 +305,42 @@ int cucul_blit(cucul_canvas_t *dst, int x, int y,
 
     for(j = startj; j < endj; j++)
     {
+        unsigned int dstix = (j + y) * dst->width + starti + x;
+        unsigned int srcix = j * src->width + starti;
+        int stride = endi - starti;
+
+        /* FIXME: we are ignoring the mask here */
+        if((starti + x) && dst->chars[dstix] == CUCUL_MAGIC_FULLWIDTH)
+            dst->chars[dstix - 1] = ' ';
+
+        if((unsigned int)(endi + x) < dst->width
+                && dst->chars[dstix + stride] == CUCUL_MAGIC_FULLWIDTH)
+            dst->chars[dstix + stride] = ' ';
+
         if(mask)
         {
-            for(i = starti; i < endi; i++)
+            for(i = 0; i < stride; i++)
             {
-                if(mask->chars[j * src->width + i] == (uint32_t)' ')
+                if(mask->chars[srcix + i] == (uint32_t)' ')
                     continue;
 
-                dst->chars[(j + y) * dst->width + (i + x)]
-                                             = src->chars[j * src->width + i];
-                dst->attr[(j + y) * dst->width + (i + x)]
-                                             = src->attr[j * src->width + i];
+                dst->chars[dstix + i] = src->chars[srcix + i];
+                dst->attr[dstix + i] = src->attr[srcix + i];
             }
         }
         else
         {
-            memcpy(dst->chars + (j + y) * dst->width + starti + x,
-                   src->chars + j * src->width + starti,
-                   (endi - starti) * 4);
-            memcpy(dst->attr + (j + y) * dst->width + starti + x,
-                   src->attr + j * src->width + starti,
-                   (endi - starti) * 4);
+            memcpy(dst->chars + dstix, src->chars + srcix, (stride) * 4);
+            memcpy(dst->attr + dstix, src->attr + srcix, (stride) * 4);
         }
+
+        /* Fix split fullwidth chars */
+        if(src->chars[srcix] == CUCUL_MAGIC_FULLWIDTH)
+            dst->chars[dstix] = ' ';
+
+        if((unsigned int)endi < src->width
+                && src->chars[endi] == CUCUL_MAGIC_FULLWIDTH)
+            dst->chars[dstix + stride - 1] = ' ';
     }
 
     return 0;
diff --git a/cucul/transform.c b/cucul/transform.c
index 30223cc..c275c1f 100644
--- a/cucul/transform.c
+++ b/cucul/transform.c
@@ -92,6 +92,7 @@ int cucul_flip(cucul_canvas_t *cv)
         if(cleft == cright)
             *cleft = flipchar(*cleft);
 
+        /* Fix fullwidth characters. Could it be done in one loop? */
         cleft = cv->chars + y * cv->width;
         cright = cleft + cv->width - 1;
         for( ; cleft < cright; cleft++)
@@ -187,6 +188,7 @@ int cucul_rotate(cucul_canvas_t *cv)
     if(cbegin == cend)
         *cbegin = rotatechar(*cbegin);
 
+    /* Fix fullwidth characters. Could it be done in one loop? */
     for(y = 0; y < cv->height; y++)
     {
         cbegin = cv->chars + y * cv->width;
diff --git a/test/fullwidth.c b/test/fullwidth.c
index 98829c0..5692025 100644
--- a/test/fullwidth.c
+++ b/test/fullwidth.c
@@ -28,7 +28,7 @@
 
 int main(int argc, char *argv[])
 {
-    cucul_canvas_t *cv, *caca;
+    cucul_canvas_t *cv, *caca, *line;
     caca_display_t *dp;
 
     unsigned int i;
@@ -37,7 +37,9 @@ int main(int argc, char *argv[])
     dp = caca_create_display(cv);
 
     caca = cucul_create_canvas(6, 10);
+    line = cucul_create_canvas(2, 1);
 
+    /* Line of x's */
     for(i = 0; i < 10; i++)
     {
         cucul_set_color(caca, CUCUL_COLOR_WHITE, CUCUL_COLOR_BLUE);
@@ -48,6 +50,7 @@ int main(int argc, char *argv[])
 
     cucul_blit(cv, 1, 1, caca, NULL);
 
+    /* Line of ホ's */
     for(i = 0; i < 10; i++)
     {
         cucul_set_color(caca, CUCUL_COLOR_WHITE, CUCUL_COLOR_BLUE);
@@ -58,11 +61,26 @@ int main(int argc, char *argv[])
 
     cucul_blit(cv, 15, 1, caca, NULL);
 
+    /* Line of canvas */
+    cucul_set_color(line, CUCUL_COLOR_WHITE, CUCUL_COLOR_MAGENTA);
+    cucul_putstr(line, 0, 0, "ほ");
+    for(i = 0; i < 10; i++)
+    {
+        cucul_set_color(caca, CUCUL_COLOR_WHITE, CUCUL_COLOR_BLUE);
+        cucul_putstr(caca, 0, i, CACA);
+        cucul_blit(caca, i - 2, i, line, NULL);
+    }
+
+    cucul_blit(cv, 29, 1, caca, NULL);
+
     caca_refresh_display(dp);
 
     caca_get_event(dp, CACA_EVENT_KEY_PRESS, NULL, -1);
 
     caca_free_display(dp);
+
+    cucul_free_canvas(line);
+    cucul_free_canvas(caca);
     cucul_free_canvas(cv);
 
     return 0;