diff --git a/Makefile b/Makefile
index 8de0032..82f2dd3 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-KFVER=1_2_3
+KFVER=1_2_4
 
 DISTDIR=kiss_fft_v$(KFVER)
 TARBALL=kiss_fft_v$(KFVER).tar.gz
diff --git a/kiss_fft.c b/kiss_fft.c
index e4c4044..f6d97ac 100644
--- a/kiss_fft.c
+++ b/kiss_fft.c
@@ -329,7 +329,7 @@ kiss_fft_cfg kiss_fft_alloc(int nfft,int inverse_fft,void * mem,size_t * lenmem
     if ( lenmem==NULL ) {
         st = ( kiss_fft_cfg)KISS_FFT_MALLOC( memneeded );
     }else{
-        if (*lenmem >= memneeded)
+        if (mem != NULL && *lenmem >= memneeded)
             st = (kiss_fft_cfg)mem;
         *lenmem = memneeded;
     }