diff -Naur fbpdf-20200617_f590024/README fbpdf-20200617_f590024.patched/README
--- fbpdf-20200617_f590024/README	2021-09-27 04:15:02.000000000 -0400
+++ fbpdf-20200617_f590024.patched/README	2021-09-29 02:31:51.610212471 -0400
@@ -21,7 +21,9 @@
 G		go to page (the last page if no prefix)
 o		set page number (for 'G' command only)
 O		set page number and go to current page
-z		zoom; prefix multiplied by 10 (i.e. '15z' = 150%)
+z/=	zoom; prefix multiplied by 10 (i.e. '12z' = 120%). Default 15.
++		increase zoom by 10%
+-		decrease zoom by 10%
 r		set rotation in degrees
 i		print some information
 I		invert colors
diff -Naur fbpdf-20200617_f590024/fbpdf.c fbpdf-20200617_f590024.patched/fbpdf.c
--- fbpdf-20200617_f590024/fbpdf.c	2021-09-27 04:15:02.000000000 -0400
+++ fbpdf-20200617_f590024.patched/fbpdf.c	2021-09-29 16:07:26.245764122 -0400
@@ -269,6 +269,7 @@
 				srow = prow;
 			break;
 		case 'z':
+		case '=':
 			count *= 10;
 			zoom_page(getcount(zoom_def));
 			break;
@@ -319,10 +320,20 @@
 		case ' ':
 		case CTRLKEY('d'):
 			srow += srows * getcount(1) - step;
+			if(srow >= (prow + prows)) {
+				srow = 0;
+				loadpage(num + 1);
+				srow = prow;
+			}
 			break;
 		case 127:
 		case CTRLKEY('u'):
 			srow -= srows * getcount(1) - step;
+			if(srow <= 0) {
+				srow = prows - step;
+				loadpage(num - 1);
+				srow = prow;
+			}
 			break;
 		case '[':
 			scol = pcol;
@@ -342,6 +353,14 @@
 			invert = !invert;
 			loadpage(num);
 			break;
+		case '+':
+			count = 0;
+			zoom_page(zoom + 1);
+			break;
+		case '-':
+			count = 0;
+			if(zoom > 0) zoom_page(zoom - 1);
+			break;
 		default:	/* no need to redraw */
 			continue;
 		}