diff --git a/celt/bands.c b/celt/bands.c
index 93bd0bc7220a86ed86f174fe02e5c2698d380df2..f22951b5c4a925e2742748e65f2122464ebf5727 100644
--- a/celt/bands.c
+++ b/celt/bands.c
@@ -492,7 +492,7 @@ int spreading_decision(const CELTMode *m, celt_norm *X, int *average,
          *tapset_decision=0;
    }
    /*printf("%d %d %d\n", hf_sum, *hf_average, *tapset_decision);*/
-   celt_assert(nbBands>0); /*M*(eBands[end]-eBands[end-1]) <= 8 assures this*/
+   celt_assert(nbBands>0); /* end has to be non-zero */
    sum /= nbBands;
    /* Recursive averaging */
    sum = (sum+*average)>>1;
@@ -869,7 +869,6 @@ static unsigned quant_partition(struct band_ctx *ctx, celt_norm *X,
    int q;
    int curr_bits;
    int imid=0, iside=0;
-   int N_B=N;
    int B0=B;
    opus_val16 mid=0, side=0;
    unsigned cm=0;
@@ -891,8 +890,6 @@ static unsigned quant_partition(struct band_ctx *ctx, celt_norm *X,
    spread = ctx->spread;
    ec = ctx->ec;
 
-   N_B /= B;
-
    /* If we need 1.5 more bit than we can produce, split the band in two. */
    cache = m->cache.bits + m->cache.index[(LM+1)*m->nbEBands+i];
    if (LM != -1 && b > cache[cache[0]]+12 && N>2)
@@ -1072,7 +1069,6 @@ static unsigned quant_band(struct band_ctx *ctx, celt_norm *X,
    longBlocks = B0==1;
 
    N_B /= B;
-   N_B0 = N_B;
 
    /* Special case for one sample */
    if (N==1)
diff --git a/celt/celt_encoder.c b/celt/celt_encoder.c
index cae87b5230a51c5c6db19e058655ee7f3fa8d7f9..4e38412880813f9b0a0f16e09a1ca827525fec77 100644
--- a/celt/celt_encoder.c
+++ b/celt/celt_encoder.c
@@ -240,7 +240,6 @@ static int transient_analysis(const opus_val32 * OPUS_RESTRICT in, int len, int
    ALLOC(tmp, len, opus_val16);
 
    len2=len/2;
-   tf_max = 0;
    for (c=0;c<C;c++)
    {
       opus_val32 mean;
diff --git a/celt/stack_alloc.h b/celt/stack_alloc.h
index 76be6006c499d2f37424a275f22efa9780cde252..316a6ce12c08d019343cd04f96ebe59b988e7da6 100644
--- a/celt/stack_alloc.h
+++ b/celt/stack_alloc.h
@@ -95,6 +95,8 @@
 #define SAVE_STACK
 #define RESTORE_STACK
 #define ALLOC_STACK
+/* C99 does not allow VLAs of size zero */
+#define ALLOC_NONE 1
 
 #elif defined(USE_ALLOCA)
 
@@ -109,6 +111,7 @@
 #define SAVE_STACK
 #define RESTORE_STACK
 #define ALLOC_STACK
+#define ALLOC_NONE 0
 
 #else
 
@@ -146,6 +149,7 @@ extern char *global_stack_top;
 #define VARDECL(type, var) type *var
 #define ALLOC(var, size, type) var = PUSH(global_stack, size, type)
 #define SAVE_STACK char *_saved_stack = global_stack;
+#define ALLOC_NONE 0
 
 #endif /* VAR_ARRAYS */
 
diff --git a/silk/dec_API.c b/silk/dec_API.c
index bb0bc07784af923205abc963565e0eea050cb1c3..4cbcf71514d376215ee8f6c5bfa8e06cb4798478 100644
--- a/silk/dec_API.c
+++ b/silk/dec_API.c
@@ -305,7 +305,7 @@ opus_int silk_Decode(                                   /* O    Returns error co
 
     /* Set up pointers to temp buffers */
     ALLOC( samplesOut2_tmp,
-           decControl->nChannelsAPI == 2 ? *nSamplesOut : 0, opus_int16 );
+           decControl->nChannelsAPI == 2 ? *nSamplesOut : ALLOC_NONE, opus_int16 );
     if( decControl->nChannelsAPI == 2 ) {
         resample_out_ptr = samplesOut2_tmp;
     } else {
diff --git a/src/analysis.c b/src/analysis.c
index 2dd087b84446e7cddaef1697d4585cbee84febf9..3ee206c9a42a8c1a130c35153df2f63002ccee93 100644
--- a/src/analysis.c
+++ b/src/analysis.c
@@ -317,7 +317,6 @@ void tonality_analysis(TonalityAnalysisState *tonal, AnalysisInfo *info_out, con
     }
     relativeE = 0;
     frame_loudness = 0;
-    bandwidth_mask = 0;
     for (b=0;b<NB_TBANDS;b++)
     {
        float E=0, tE=0, nE=0;
@@ -597,7 +596,6 @@ void tonality_analysis(TonalityAnalysisState *tonal, AnalysisInfo *info_out, con
           if (tonal->speech_confidence_count==0)
              tonal->speech_confidence = .1f;
        }
-       psum = MAX16(tonal->speech_confidence, MIN16(tonal->music_confidence, psum));
     }
     if (tonal->last_music != (tonal->music_prob>.5f))
        tonal->last_transition=0;
diff --git a/src/opus_decoder.c b/src/opus_decoder.c
index fc6f7b04f7174ed42bc3be6aaff246f9ad3b9252..e7964e3da6b97561febafe9c253cc002ee1a6176 100644
--- a/src/opus_decoder.c
+++ b/src/opus_decoder.c
@@ -297,8 +297,8 @@ static int opus_decode_frame(OpusDecoder *st, const unsigned char *data,
       }
    }
 
-   pcm_transition_silk_size = 0;
-   pcm_transition_celt_size = 0;
+   pcm_transition_silk_size = ALLOC_NONE;
+   pcm_transition_celt_size = ALLOC_NONE;
    if (data!=NULL && st->prev_mode > 0 && (
        (mode == MODE_CELT_ONLY && st->prev_mode != MODE_CELT_ONLY && !st->prev_redundancy)
     || (mode != MODE_CELT_ONLY && st->prev_mode == MODE_CELT_ONLY) )
@@ -327,7 +327,7 @@ static int opus_decode_frame(OpusDecoder *st, const unsigned char *data,
    }
 
    /* Don't allocate any memory when in CELT-only mode */
-   pcm_silk_size = (mode != MODE_CELT_ONLY) ? IMAX(F10, frame_size)*st->channels : 0;
+   pcm_silk_size = (mode != MODE_CELT_ONLY) ? IMAX(F10, frame_size)*st->channels : ALLOC_NONE;
    ALLOC(pcm_silk, pcm_silk_size, opus_int16);
 
    /* SILK processing */