diff --git a/sprintf.c b/sprintf.c
index 92738783eb..c8522ddf4b 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -1136,7 +1136,7 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 			expr = "Inf";
 		    }
 		    need = (int)strlen(expr);
-		    if ((!isnan(fval) && fval < 0.0) || (flags & FPLUS))
+		    if ((!isnan(fval) && fval < 0.0) || (flags & (FPLUS|FSPACE)))
 			need++;
 		    if ((flags & FWIDTH) && need < width)
 			need = width;
@@ -1157,8 +1157,6 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 			    buf[blen + need - strlen(expr) - 1] = '-';
 			else if (flags & FPLUS)
 			    buf[blen + need - strlen(expr) - 1] = '+';
-			else if ((flags & FSPACE) && need > width)
-			    blen++;
 			memcpy(&buf[blen + need - strlen(expr)], expr,
 			       strlen(expr));
 		    }
diff --git a/test/ruby/test_sprintf.rb b/test/ruby/test_sprintf.rb
index c80f88b15e..1bf65f1eab 100644
--- a/test/ruby/test_sprintf.rb
+++ b/test/ruby/test_sprintf.rb
@@ -84,6 +84,18 @@ class TestSprintf < Test::Unit::TestCase
     assert_equal("NaN", sprintf("%-f", nan))
     assert_equal("+NaN", sprintf("%+f", nan))
 
+    assert_equal("NaN", sprintf("%3f", nan))
+    assert_equal("NaN", sprintf("%-3f", nan))
+    assert_equal("+NaN", sprintf("%+3f", nan))
+
+    assert_equal(" NaN", sprintf("% 3f", nan))
+    assert_equal(" NaN", sprintf("%- 3f", nan))
+    assert_equal("+NaN", sprintf("%+ 3f", nan))
+
+    assert_equal(" NaN", sprintf("% 03f", nan))
+    assert_equal(" NaN", sprintf("%- 03f", nan))
+    assert_equal("+NaN", sprintf("%+ 03f", nan))
+
     assert_equal("     NaN", sprintf("%8f", nan))
     assert_equal("NaN     ", sprintf("%-8f", nan))
     assert_equal("    +NaN", sprintf("%+8f", nan))
@@ -107,6 +119,26 @@ class TestSprintf < Test::Unit::TestCase
     assert_equal("Inf", sprintf("%-f", inf))
     assert_equal("+Inf", sprintf("%+f", inf))
 
+    assert_equal(" Inf", sprintf("% f", inf))
+    assert_equal(" Inf", sprintf("%- f", inf))
+    assert_equal("+Inf", sprintf("%+ f", inf))
+
+    assert_equal(" Inf", sprintf("% 0f", inf))
+    assert_equal(" Inf", sprintf("%- 0f", inf))
+    assert_equal("+Inf", sprintf("%+ 0f", inf))
+
+    assert_equal("Inf", sprintf("%3f", inf))
+    assert_equal("Inf", sprintf("%-3f", inf))
+    assert_equal("+Inf", sprintf("%+3f", inf))
+
+    assert_equal(" Inf", sprintf("% 3f", inf))
+    assert_equal(" Inf", sprintf("%- 3f", inf))
+    assert_equal("+Inf", sprintf("%+ 3f", inf))
+
+    assert_equal(" Inf", sprintf("% 03f", inf))
+    assert_equal(" Inf", sprintf("%- 03f", inf))
+    assert_equal("+Inf", sprintf("%+ 03f", inf))
+
     assert_equal("     Inf", sprintf("%8f", inf))
     assert_equal("Inf     ", sprintf("%-8f", inf))
     assert_equal("    +Inf", sprintf("%+8f", inf))
@@ -127,6 +159,26 @@ class TestSprintf < Test::Unit::TestCase
     assert_equal("-Inf", sprintf("%-f", -inf))
     assert_equal("-Inf", sprintf("%+f", -inf))
 
+    assert_equal("-Inf", sprintf("% f", -inf))
+    assert_equal("-Inf", sprintf("%- f", -inf))
+    assert_equal("-Inf", sprintf("%+ f", -inf))
+
+    assert_equal("-Inf", sprintf("% 0f", -inf))
+    assert_equal("-Inf", sprintf("%- 0f", -inf))
+    assert_equal("-Inf", sprintf("%+ 0f", -inf))
+
+    assert_equal("-Inf", sprintf("%4f", -inf))
+    assert_equal("-Inf", sprintf("%-4f", -inf))
+    assert_equal("-Inf", sprintf("%+4f", -inf))
+
+    assert_equal("-Inf", sprintf("% 4f", -inf))
+    assert_equal("-Inf", sprintf("%- 4f", -inf))
+    assert_equal("-Inf", sprintf("%+ 4f", -inf))
+
+    assert_equal("-Inf", sprintf("% 04f", -inf))
+    assert_equal("-Inf", sprintf("%- 04f", -inf))
+    assert_equal("-Inf", sprintf("%+ 04f", -inf))
+
     assert_equal("    -Inf", sprintf("%8f", -inf))
     assert_equal("-Inf    ", sprintf("%-8f", -inf))
     assert_equal("    -Inf", sprintf("%+8f", -inf))