diff --git a/src/math/special/scalbn.h b/src/math/special/scalbn.h
index f6f6755..ce0ddbf 100644
--- a/src/math/special/scalbn.h
+++ b/src/math/special/scalbn.h
@@ -15,3 +15,5 @@ T(RN,                    -inf,  2147483647,                    -inf,          0x
 T(RN,               0x1p+1023,       -2097,               0x1p-1074,          0x0p+0, 0)
 T(RN,               0x1p-1074,        2097,               0x1p+1023,          0x0p+0, 0)
 T(RN,              0x1.001p+0,       -1074,               0x1p-1074,          0x0p+0, INEXACT|UNDERFLOW)
+T(RN,    0x1.7ffffffffffffp-1,       -1073,               0x1p-1074,          0x0p+0, INEXACT|UNDERFLOW)
+T(RN,    0x1.000000000000bp-1,       -1024, 0x1.0000000000008p-1025,          0x0p+0, INEXACT|UNDERFLOW)
diff --git a/src/math/special/scalbnf.h b/src/math/special/scalbnf.h
index 24b423f..4ccbf19 100644
--- a/src/math/special/scalbnf.h
+++ b/src/math/special/scalbnf.h
@@ -15,3 +15,5 @@ T(RN,            -inf,  2147483647,            -inf,          0x0p+0, 0)
 T(RN,        0x1p+127,        -276,        0x1p-149,          0x0p+0, 0)
 T(RN,        0x1p-149,         276,        0x1p+127,          0x0p+0, 0)
 T(RN,      0x1.001p+0,        -149,        0x1p-149,          0x0p+0, INEXACT|UNDERFLOW)
+T(RN,   0x1.7ffffep-1,        -148,        0x1p-149,          0x0p+0, INEXACT|UNDERFLOW)
+T(RN,   0x1.000016p-1,        -128,  0x1.00001p-129,          0x0p+0, INEXACT|UNDERFLOW)
diff --git a/src/math/special/scalbnl.h b/src/math/special/scalbnl.h
index d69bdd2..7a67295 100644
--- a/src/math/special/scalbnl.h
+++ b/src/math/special/scalbnl.h
@@ -15,3 +15,5 @@ T(RN,                           -inf,  2147483647,                           -in
 T(RN,                    0x1p+16383L,      -32828,                    0x1p-16445L,          0x0p+0, 0)
 T(RN,                    0x1p-16445L,       32828,                    0x1p+16383L,          0x0p+0, 0)
 T(RN,            0x1.00000000001p+0L,      -16445,                    0x1p-16445L,          0x0p+0, INEXACT|UNDERFLOW)
+T(RN,       0x1.7ffffffffffffffep-1L,      -16444,                    0x1p-16445L,          0x0p+0, INEXACT|UNDERFLOW)
+T(RN,       0x1.0000000000000016p-1L,      -16384,    0x1.000000000000001p-16385L,          0x0p+0, INEXACT|UNDERFLOW)