diff --git a/core/math/expm1_spec.rb b/core/math/expm1_spec.rb
new file mode 100644
index 000000000..5725319ab
--- /dev/null
+++ b/core/math/expm1_spec.rb
@@ -0,0 +1,37 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+ruby_version_is "4.0" do
+  describe "Math.expm1" do
+    it "calculates Math.exp(arg) - 1" do
+      Math.expm1(3).should == Math.exp(3) - 1
+    end
+
+    it "preserves precision that can be lost otherwise" do
+      Math.expm1(1.0e-16).should be_close(1.0e-16, TOLERANCE)
+      Math.expm1(1.0e-16).should != 0.0
+    end
+
+    it "raises a TypeError if the argument cannot be coerced with Float()" do
+      -> { Math.expm1("test") }.should raise_error(TypeError, "can't convert String into Float")
+    end
+
+    it "returns NaN given NaN" do
+      Math.expm1(nan_value).nan?.should be_true
+    end
+
+    it "raises a TypeError if the argument is nil" do
+      -> { Math.expm1(nil) }.should raise_error(TypeError, "can't convert nil into Float")
+    end
+
+    it "accepts any argument that can be coerced with Float()" do
+      Math.expm1(MathSpecs::Float.new).should be_close(Math::E - 1, TOLERANCE)
+    end
+  end
+
+  describe "Math#expm1" do
+    it "is accessible as a private instance method" do
+      IncludesMath.new.send(:expm1, 23.1415).should be_close(11226018483.0012, TOLERANCE)
+    end
+  end
+end
diff --git a/core/math/log1p_spec.rb b/core/math/log1p_spec.rb
new file mode 100644
index 000000000..216358a3c
--- /dev/null
+++ b/core/math/log1p_spec.rb
@@ -0,0 +1,49 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+ruby_version_is "4.0" do
+  describe "Math.log1p" do
+    it "calculates Math.log(1 + arg)" do
+      Math.log1p(3).should == Math.log(1 + 3)
+    end
+
+    it "preserves precision that can be lost otherwise" do
+      Math.log1p(1e-16).should be_close(1.0e-16, TOLERANCE)
+      Math.log1p(1e-16).should != 0.0
+    end
+
+    it "raises an Math::DomainError if the argument is less than 1" do
+      -> { Math.log1p(-1-1e-15) }.should raise_error(Math::DomainError, "Numerical argument is out of domain - log1p")
+    end
+
+    it "raises a TypeError if the argument cannot be coerced with Float()" do
+      -> { Math.log1p("test") }.should raise_error(TypeError, "can't convert String into Float")
+    end
+
+    it "raises a TypeError for numerical values passed as string" do
+      -> { Math.log1p("10") }.should raise_error(TypeError, "can't convert String into Float")
+    end
+
+    it "does not accept a second argument for the base" do
+      -> { Math.log1p(9, 3) }.should raise_error(ArgumentError, "wrong number of arguments (given 2, expected 1)")
+    end
+
+    it "returns NaN given NaN" do
+      Math.log1p(nan_value).nan?.should be_true
+    end
+
+    it "raises a TypeError if the argument is nil" do
+      -> { Math.log1p(nil) }.should raise_error(TypeError, "can't convert nil into Float")
+    end
+
+    it "accepts any argument that can be coerced with Float()" do
+      Math.log1p(MathSpecs::Float.new).should be_close(0.6931471805599453, TOLERANCE)
+    end
+  end
+
+  describe "Math#log1p" do
+    it "is accessible as a private instance method" do
+      IncludesMath.new.send(:log1p, 4.21).should be_close(1.65057985576528, TOLERANCE)
+    end
+  end
+end