diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4d583cb..e44f97b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -127,3 +127,5 @@ add_test(NAME core_synthesis_mag
          COMMAND sh -c "cd ${CMAKE_CURRENT_SOURCE_DIR}/unittest; SYNTH_mag=1 ./test_core_nn.sh")
 add_test(NAME nnet2f32
          COMMAND sh -c "cd ${CMAKE_CURRENT_BINARY_DIR}; ./src/nnet2f32 t.f32")
+add_test(NAME SIMD_functions
+         COMMAND sh -c "cd ${CMAKE_CURRENT_BINARY_DIR}; ./src/test_vec")
diff --git a/README.md b/README.md
index 5bbe838..4d8ce54 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,14 @@ LPCNet at 1733 bits/s using direct-split quantiser:
 ```
 sox ../../wav/wia.wav -t raw -r 16000 - | ./lpcnet_enc -s | ./lpcnet_dec -s | aplay -f S16_LE -r 16000
 ```
+# CTests
+
+```
+$ cd ~/LPCNet/build_linux
+$ ctest
+```
+
+Note, due to precision/library issues several tests (1-3) will only pass on certain machines such as Ubuntu 16 and 18, Ubuntu 17 is known to fail.
 
 # Reading Further
 
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index cae16b5..e39b2de 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -77,6 +77,9 @@ target_link_libraries(quant2c m)
 add_executable(diff32 diff32.c)
 target_link_libraries(diff32 m)
 
+add_executable(ramp ramp.c)
+target_link_libraries(ramp m)
+
 add_executable(quant_enc quant_enc.c)
 target_link_libraries(quant_enc lpcnetfreedv m codec2)
 
diff --git a/src/quant_feat.c b/src/quant_feat.c
index cc2883c..2c74e41 100644
--- a/src/quant_feat.c
+++ b/src/quant_feat.c
@@ -422,10 +422,7 @@ int main(int argc, char *argv[]) {
             float tmp[NB_BANDS];
             dct(tmp, features_out);
             for(i=0; i<NB_BANDS; i++) features_out[i] = tmp[i];
-       }
-
-        /* need to recompute LPCs after every frame, as we have quantised, or interpolated */
-        lpc_from_cepstrum(&features_out[2*NB_BANDS+3], features_out);
+        }
 
         for(i=0; i<NB_FEATURES; i++) {
             if (isnan(features_out[i])) {
diff --git a/src/ramp.c b/src/ramp.c
new file mode 100644
index 0000000..da6f0b7
--- /dev/null
+++ b/src/ramp.c
@@ -0,0 +1,26 @@
+/* generates a linear ramp to test quant_feat decimation/interpolation */
+
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#define NB_FEATURES 55
+#define FRAMES      18
+
+int main(void) {
+    FILE *fout = fopen("ramp.f32", "wb"); assert(fout != NULL);
+    float features[NB_FEATURES];
+    int i,j;
+    
+    for(i=0; i<FRAMES; i++) {
+        for(j=0; j<NB_FEATURES; j++)
+            features[j] = i+j;
+        fwrite(features, sizeof(float), NB_FEATURES, fout);
+    }
+    
+    fclose(fout);
+
+    return 0;
+}
diff --git a/src/test_lpcnet.c b/src/test_lpcnet.c
index 08baac2..0a34729 100644
--- a/src/test_lpcnet.c
+++ b/src/test_lpcnet.c
@@ -74,7 +74,7 @@ int main(int argc, char **argv) {
 
     if ((argc - dx) < 2) {
     helpmsg:
-        fprintf(stderr, "usage: test_lpcnet [--mag] [--logstates statesfile] <features.f32> <output.pcm>\n");
+        fprintf(stderr, "usage: test_lpcnet [--mag] [--logstates statesfile] [--nnet lpcnet_xxx.f32] <features.f32> <output.pcm>\n");
         return 0;
     }