diff --git a/simgear/math/simd.hxx b/simgear/math/simd.hxx
index 0ec604e8..7cef6fb2 100644
--- a/simgear/math/simd.hxx
+++ b/simgear/math/simd.hxx
@@ -1085,7 +1085,7 @@ inline simd4_t<int,N> max(simd4_t<int,N> v1, const simd4_t<int,N>& v2) {
 # endif
 
 # ifdef __ARM_NEON__
-#  include "simd_neon.hxx"
+#  include <simgear/math/simd_neon.hxx>
 # endif
 
 #endif /* __SIMD_H__ */
diff --git a/simgear/math/simd_neon.hxx b/simgear/math/simd_neon.hxx
index 11a2614b..608cd219 100644
--- a/simgear/math/simd_neon.hxx
+++ b/simgear/math/simd_neon.hxx
@@ -48,20 +48,15 @@ private:
 
 public:
     simd4_t(void) {}
-    simd4_t(float f) {
-        simd4 = vdupq_n_f32(f);
-        for (int i=N; i<4; ++i) _v4[i] = 0.0f;
-    }
+    simd4_t(float f) {}
     simd4_t(float x, float y) : simd4_t(x,y,0,0) {}
     simd4_t(float x, float y, float z) : simd4_t(x,y,z,0) {}
     simd4_t(float x, float y, float z, float w) {
         _v4[0] = x; _v4[1] = y; _v4[2] = z; _v4[3] = w;
     }
-    simd4_t(const __vec4f_t v) {
-        simd4 = vld1q_f32(v);
-        for (int i=N; i<4; ++i) _v4[i] = 0.0f;
-    }
-    simd4_t(const simd4_t<float,N>& v) {
+    simd4_t(const __vec4f_t v) {}
+    template<int M>
+    simd4_t(const simd4_t<float,M>& v) {
         simd4 = v.v4();
     }
     simd4_t(const float32x4_t& v) {
@@ -89,25 +84,6 @@ public:
         return vec;
     }
 
-    inline simd4_t<float,N>& operator=(float f) {
-        simd4 = vdupq_n_f32(f);
-        for (int i=N; i<4; ++i) _v4[i] = 0.0f;
-        return *this;
-    }
-    inline simd4_t<float,N>& operator=(const __vec4f_t v) {
-        simd4 = vld1q_f32(v);
-        for (int i=N; i<4; ++i) _v4[i] = 0.0f;
-        return *this;
-    }
-    inline simd4_t<float,N>& operator=(const simd4_t<float,N>& v) {
-        simd4 = v.v4();
-        return *this;
-    }
-    inline simd4_t<float,N>& operator=(const float32x4_t& v) {
-        simd4 = v;
-        return *this;
-    }
-
     inline simd4_t<float,N>& operator+=(float f) {
         return operator+=(simd4_t<float,N>(f));
     }
@@ -149,6 +125,9 @@ public:
     }
 };
 
+simd4 = vdupq_n_f32(f);
+simd4 = vld1q_f32(v);
+
 namespace simd4
 {
 // http://stackoverflow.com/questions/6931217/sum-all-elements-in-a-quadword-vector-in-arm-assembly-with-neon