diff --git a/config.h.in b/config.h.in
index b9c7e0c..ead1f1f 100644
--- a/config.h.in
+++ b/config.h.in
@@ -24,6 +24,9 @@
 /* Define if you want your background to use the parent window background */
 #undef ENABLE_TRANSPARENCY
 
+/* Define if you want add space when testing character width */
+#undef ENABLE_USE_SPACE
+
 /* Define if you want to display wide glyphs */
 #undef ENABLE_WIDE_GLYPHS
 
diff --git a/configure b/configure
index 6b50a6b..a89170f 100755
--- a/configure
+++ b/configure
@@ -741,6 +741,7 @@ enable_font_styles
 enable_wide_glyphs
 enable_font_width
 enable_line_spacing
+enable_use_space
 enable_pixbuf
 enable_startup_notification
 enable_transparency
@@ -1418,6 +1419,7 @@ Optional Features:
   --enable-wide-glyphs    enable displaying of wide glyphs
   --enable-font-width     enable proper way to calculate character width
   --enable-line-spacing   enable line spacing fix
+  --enable-use-space      enable add space to extent test characters
   --enable-pixbuf         enable integration with gdk-pixbuf for background images
   --enable-startup-notification  enable freedesktop startup notification support
   --enable-transparency   enable transparent backgrounds
@@ -5001,6 +5003,7 @@ support_iso14755=yes
 support_styles=yes
 support_font_width=no
 support_line_spacing=no
+support_use_space=no
 support_perl=yes
 codesets=all
 
@@ -5034,6 +5037,7 @@ then :
        support_wide_glyphs=no
        support_font_width=no
        support_line_spacing=no
+       support_use_space=no
        support_perl=no
        codesets=
     fi
@@ -5062,6 +5066,7 @@ then :
        support_wide_glyphs=yes
        support_font_width=yes
        support_line_spacing=yes
+       support_use_space=yes
        support_perl=yes
        codesets=all
     fi
@@ -5205,6 +5210,15 @@ then :
 fi
 
 
+# Check whether --enable-use-space was given.
+if test ${enable_use_space+y}
+then :
+  enableval=$enable_use_space; if test x$enableval = xyes -o x$enableval = xno; then
+    support_use_space=$enableval
+  fi
+fi
+
+
 # Check whether --enable-pixbuf was given.
 if test ${enable_pixbuf+y}
 then :
@@ -7719,6 +7733,11 @@ if test x$support_line_spacing = xyes; then
 
 printf "%s\n" "#define ENABLE_LINE_SPACING 1" >>confdefs.h
 
+fi
+if test x$support_use_space = xyes; then
+
+printf "%s\n" "#define ENABLE_USE_SPACE 1" >>confdefs.h
+
 fi
 if test x$support_iso14755 = xyes; then
 
diff --git a/configure.ac b/configure.ac
index 1cffda6..f623818 100644
--- a/configure.ac
+++ b/configure.ac
@@ -92,6 +92,7 @@ support_iso14755=yes
 support_styles=yes
 support_font_width=no
 support_line_spacing=no
+support_use_space=no
 support_perl=yes
 codesets=all
 
@@ -128,6 +129,7 @@ AC_ARG_ENABLE(everything,
        support_wide_glyphs=no
        support_font_width=no
        support_line_spacing=no
+       support_use_space=no
        support_perl=no
        codesets=
     fi
@@ -156,6 +158,7 @@ AC_ARG_ENABLE(everything,
        support_wide_glyphs=yes
        support_font_width=yes
        support_line_spacing=yes
+       support_use_space=yes
        support_perl=yes
        codesets=all
     fi
@@ -247,6 +250,12 @@ AC_ARG_ENABLE(line-spacing,
     support_line_spacing=$enableval
   fi])
 
+AC_ARG_ENABLE(use-space,
+  [  --enable-use-space      enable add space to extent test characters],
+  [if test x$enableval = xyes -o x$enableval = xno; then
+    support_use_space=$enableval
+  fi])
+
 AC_ARG_ENABLE(pixbuf,
   [  --enable-pixbuf         enable integration with gdk-pixbuf for background images],
   [if test x$enableval = xyes -o x$enableval = xno; then
@@ -678,6 +687,9 @@ fi
 if test x$support_line_spacing = xyes; then
   AC_DEFINE(ENABLE_LINE_SPACING, 1, Define if you want line spacing fix)
 fi
+if test x$support_use_space = xyes; then
+  AC_DEFINE(ENABLE_USE_SPACE, 1, Define if you want add space when testing character width)
+fi
 if test x$support_iso14755 = xyes; then
   AC_DEFINE(ISO_14755, 1, Define if you want ISO 14755 extended support)
 fi
diff --git a/src/rxvtfont.C b/src/rxvtfont.C
index 9420a22..27b0958 100644
--- a/src/rxvtfont.C
+++ b/src/rxvtfont.C
@@ -155,7 +155,11 @@ static const struct rxvt_fallback_font {
 // these characters are used to guess the font height and width
 // pango uses a similar algorithm and doesn't trust the font either.
 static uint16_t extent_test_chars[] = {
+#ifdef ENABLE_USE_SPACE
+  ' ', '0', '1', '8', 'a', 'd', 'x', 'm', 'y', 'g', 'W', 'X', '\'', '_',
+#else
   '0', '1', '8', 'a', 'd', 'x', 'm', 'y', 'g', 'W', 'X', '\'', '_',
+#endif
   0x00cd, 0x00d5, 0x0114, 0x0177, 0x0643,	// ÍÕĔŷﻙ
   0x304c, 0x672c,				// が本
 };