diff --git a/src/renderer.c b/src/renderer.c
index 16b0a0c8..e16d07d7 100644
--- a/src/renderer.c
+++ b/src/renderer.c
@@ -55,13 +55,13 @@ static const char *const get_ft_error(FT_Error err) {
 #define MAX_UNICODE 0x10FFFF
 // number of rows and columns in the codepoint map
 #define CHARMAP_ROW 128
-#define CHARMAP_COL (MAX_UNICODE / CHARMAP_ROW)
+#define CHARMAP_COL ((unsigned int)ceil((float)MAX_UNICODE / CHARMAP_ROW))
 
 // the maximum number of glyphs for OpenType
 #define MAX_GLYPHS 65535
 // number of rows and columns in the glyph map
 #define GLYPHMAP_ROW 128
-#define GLYPHMAP_COL (MAX_GLYPHS / GLYPHMAP_ROW)
+#define GLYPHMAP_COL ((unsigned int)ceil((float)MAX_GLYPHS / GLYPHMAP_ROW))
 
 // number of subpixel bitmaps
 #define SUBPIXEL_BITMAPS_CACHED 3