diff --git a/simgear/math/CMakeLists.txt b/simgear/math/CMakeLists.txt
index d6bf513b..6a5a6ef6 100644
--- a/simgear/math/CMakeLists.txt
+++ b/simgear/math/CMakeLists.txt
@@ -46,6 +46,10 @@ simgear_component(math math "${SOURCES}" "${HEADERS}")
 
 if(ENABLE_TESTS)
 
+add_executable(sgvec4_test test_sgvec4.cxx)
+target_link_libraries(sgvec4_test ${TEST_LIBS})
+add_test(sgvec4 ${EXECUTABLE_OUTPUT_PATH}/sgvec4_test)
+
 add_executable(math_test SGMathTest.cxx)
 target_link_libraries(math_test ${TEST_LIBS})
 add_test(math ${EXECUTABLE_OUTPUT_PATH}/math_test)
diff --git a/simgear/math/test_sgvec4.cxx b/simgear/math/test_sgvec4.cxx
new file mode 100644
index 00000000..b4c2570b
--- /dev/null
+++ b/simgear/math/test_sgvec4.cxx
@@ -0,0 +1,71 @@
+
+#include <stdio.h>
+#include <cmath>
+#include <cfloat>
+
+#include "SGVec3.hxx"
+#include "SGVec4.hxx"
+
+#define TEST(a, p,q,r,s) \
+ if (a[0] != p || a[1] != q || a[2] != r || a[3] != s) \
+  printf("line: %i, diff: %5.4e, %5.4e, %5.4e, %5.4e\n", __LINE__, fabsf(a[0]-p), fabsf(a[1]-q), fabsf(a[2]-r), fabsf(a[3]-s));
+
+int main()
+{
+    float p[4] = { 1.03f, 0.55f, 0.707f, -0.01f };
+    const SGVec4f q( 0.31, 0.43, 0.69, 1.0 );
+    SGVec4<float> v(p), x(p), y(p);
+    float f, g;
+
+    TEST(x, p[0], p[1], p[2], p[3]);
+ 
+    x += q;
+    TEST(x, p[0]+q[0], p[1]+q[1], p[2]+q[2], p[3]+q[3]);
+
+    y -= q;
+    TEST(y, p[0]-q[0], p[1]-q[1], p[2]-q[2], p[3]-q[3]);
+
+    v = x; x *= 1.7f;
+    TEST(x, v[0]*1.7f, v[1]*1.7f, v[2]*1.7f, v[3]*1.7f);
+
+    v = y; y /= -.3f;
+    TEST(y, v[0]/-.3f, v[1]/-.3f, v[2]/-.3f, v[3]/-.3f);
+
+    v = +x;
+    TEST(v, x[0], x[1], x[2], x[3]);
+
+    v = -x;
+    TEST(v, -x[0], -x[1], -x[2], -x[3]);
+
+    v = y+x;
+    TEST(v, y[0]+x[0], y[1]+x[1], y[2]+x[2], y[3]+x[3]);
+
+    y = v*1.7f;
+    TEST(y, v[0]*1.7f, v[1]*1.7f, v[2]*1.7f, v[3]*1.7f);
+
+    y = 1.7f*v;
+    TEST(y, v[0]*1.7f, v[1]*1.7f, v[2]*1.7f, v[3]*1.7f);
+
+    v = y-x;
+    TEST(v, y[0]-x[0], y[1]-x[1], y[2]-x[2], y[3]-x[3]);
+
+    f = dot(x, v);
+    g = (x[0]*v[0] + x[1]*v[1] + x[2]*v[2] + x[3]*v[3]);
+    if (f != g) {
+        printf("line: %i: dot: f: %5.4f, g: %5.4f\n", __LINE__, f, g);
+    }
+
+    f = dot(v, v);
+    g = (v[0]*v[0] + v[1]*v[1] + v[2]*v[2] + v[3]*v[3]);
+    if (f != g) {
+        printf("line: %i: dot: f: %5.4f, g: %5.4f\n", __LINE__, f, g);
+    }
+    
+    x = v; v -= y;
+    SGVec4<float> t = x - y;
+    f = dot(v, v);
+    g = (t[0]*t[0] + t[1]*t[1] + t[2]*t[2] + t[3]*t[3]);
+    if (f != g) {
+        printf("line: %i: dot: f: %5.4f, g: %5.4f\n", __LINE__, f, g);
+    }
+}