diff --git a/htscodecs/arith_dynamic.c b/htscodecs/arith_dynamic.c
index 5f4b25d..f0d1aeb 100644
--- a/htscodecs/arith_dynamic.c
+++ b/htscodecs/arith_dynamic.c
@@ -678,6 +678,11 @@ unsigned char *arith_compress_to(unsigned char *in,  unsigned int in_size,
     unsigned int c_meta_len;
     uint8_t *rle = NULL, *packed = NULL;
 
+    if (in_size > INT_MAX) {
+        *out_size = 0;
+        return NULL;
+    }
+
     if (!out) {
         *out_size = arith_compress_bound(in_size, order);
         if (!(out = malloc(*out_size)))
diff --git a/htscodecs/fqzcomp_qual.c b/htscodecs/fqzcomp_qual.c
index 2225437..ec7ae74 100644
--- a/htscodecs/fqzcomp_qual.c
+++ b/htscodecs/fqzcomp_qual.c
@@ -1478,6 +1478,11 @@ unsigned char *uncompress_block_fqz2f(fqz_slice *s,
 
 char *fqz_compress(int vers, fqz_slice *s, char *in, size_t uncomp_size,
                    size_t *comp_size, int strat, fqz_gparams *gp) {
+    if (uncomp_size > INT_MAX) {
+        *comp_size = 0;
+        return NULL;
+    }
+
     return (char *)compress_block_fqz2f(vers, strat, s, (unsigned char *)in,
                                         uncomp_size, comp_size, gp);
 }
diff --git a/htscodecs/rANS_static.c b/htscodecs/rANS_static.c
index 9af3804..9865022 100644
--- a/htscodecs/rANS_static.c
+++ b/htscodecs/rANS_static.c
@@ -89,7 +89,7 @@ unsigned char *rans_compress_O0(unsigned char *in, unsigned int in_size,
     if (!out_buf)
         return NULL;
 
-    ptr = out_end = out_buf + (int)(1.05*in_size) + 257*257*3 + 9;
+    ptr = out_end = out_buf + (uint32_t)(1.05*in_size) + 257*257*3 + 9;
 
     // Compute statistics
     hist8(in, in_size, (uint32_t *)F);
@@ -401,7 +401,7 @@ unsigned char *rans_compress_O1(unsigned char *in, unsigned int in_size,
     out_buf = malloc(1.05*in_size + 257*257*3 + 9);
     if (!out_buf) goto cleanup;
 
-    out_end = out_buf + (int)(1.05*in_size) + 257*257*3 + 9;
+    out_end = out_buf + (uint32_t)(1.05*in_size) + 257*257*3 + 9;
     cp = out_buf+9;
 
     hist1_4(in, in_size, (uint32_t (*)[256])F, (uint32_t *)T);
@@ -815,6 +815,11 @@ unsigned char *rans_uncompress_O1(unsigned char *in, unsigned int in_size,
  */
 unsigned char *rans_compress(unsigned char *in, unsigned int in_size,
                              unsigned int *out_size, int order) {
+    if (in_size > INT_MAX) {
+        *out_size = 0;
+        return NULL;
+    }
+
     return order
         ? rans_compress_O1(in, in_size, out_size)
         : rans_compress_O0(in, in_size, out_size);
diff --git a/htscodecs/rANS_static16_int.h b/htscodecs/rANS_static16_int.h
index 43b89d7..ce8b28b 100644
--- a/htscodecs/rANS_static16_int.h
+++ b/htscodecs/rANS_static16_int.h
@@ -78,7 +78,8 @@ unsigned char *rans_compress_O0_4x16(unsigned char *in, unsigned int in_size,
 unsigned char *rans_uncompress_O0_4x16(unsigned char *in, unsigned int in_size,
                                        unsigned char *out, unsigned int out_sz);
 
-int rans_compute_shift(uint32_t *F0, uint32_t (*F)[256], uint32_t *T, int *S);
+int rans_compute_shift(uint32_t *F0, uint32_t (*F)[256], uint32_t *T,
+                       uint32_t *S);
 
 // Rounds to next power of 2.
 // credit to http://graphics.stanford.edu/~seander/bithacks.html
@@ -362,7 +363,7 @@ static inline int encode_freq1(uint8_t *in, uint32_t in_size, int Nway,
 
     // Decide between 10-bit and 12-bit freqs.
     // Fills out S[] to hold the new scaled maximum value.
-    int S[256] = {0};
+    uint32_t S[256] = {0};
     int shift = rans_compute_shift(T, F, T, S);
 
     // Normalise so T[i] == TOTFREQ_O1
@@ -372,7 +373,7 @@ static inline int encode_freq1(uint8_t *in, uint32_t in_size, int Nway,
         if (T[i] == 0)
             continue;
 
-        int max_val = S[i];
+        uint32_t max_val = S[i];
         if (shift == TF_SHIFT_O1_FAST && max_val > TOTFREQ_O1_FAST)
             max_val = TOTFREQ_O1_FAST;
 
diff --git a/htscodecs/rANS_static32x16pr_avx2.c b/htscodecs/rANS_static32x16pr_avx2.c
index 052eda4..2dd14f1 100644
--- a/htscodecs/rANS_static32x16pr_avx2.c
+++ b/htscodecs/rANS_static32x16pr_avx2.c
@@ -138,7 +138,7 @@ unsigned char *rans_compress_O0_32x16_avx2(unsigned char *in,
     uint32_t F[256+MAGIC] = {0};
     int i, j, tab_size = 0, x, z;
     // -20 for order/size/meta
-    int bound = rans_compress_bound_4x16(in_size,0)-20;
+    uint32_t bound = rans_compress_bound_4x16(in_size,0)-20;
 
     if (!out) {
         *out_size = bound;
@@ -693,7 +693,8 @@ unsigned char *rans_compress_O1_32x16_avx2(unsigned char *in, unsigned int in_si
                                            unsigned char *out, unsigned int *out_size) {
     unsigned char *cp, *out_end, *out_free = NULL;
     unsigned int tab_size;
-    int bound = rans_compress_bound_4x16(in_size,1)-20, z;
+    uint32_t bound = rans_compress_bound_4x16(in_size,1)-20;
+    int z;
     RansState ransN[NX] __attribute__((aligned(32)));
 
     if (in_size < NX) // force O0 instead
diff --git a/htscodecs/rANS_static32x16pr_avx512.c b/htscodecs/rANS_static32x16pr_avx512.c
index 714d4cc..0d1456f 100644
--- a/htscodecs/rANS_static32x16pr_avx512.c
+++ b/htscodecs/rANS_static32x16pr_avx512.c
@@ -66,7 +66,7 @@ unsigned char *rans_compress_O0_32x16_avx512(unsigned char *in,
     uint32_t F[256+MAGIC] = {0};
     int i, j, tab_size = 0, x, z;
     // -20 for order/size/meta
-    int bound = rans_compress_bound_4x16(in_size,0)-20;
+    uint32_t bound = rans_compress_bound_4x16(in_size,0)-20;
 
     if (!out) {
         *out_size = bound;
@@ -444,7 +444,8 @@ unsigned char *rans_compress_O1_32x16_avx512(unsigned char *in,
                                              unsigned int *out_size) {
     unsigned char *cp, *out_end, *out_free = NULL;
     unsigned int tab_size;
-    int bound = rans_compress_bound_4x16(in_size,1)-20, z;
+    uint32_t bound = rans_compress_bound_4x16(in_size,1)-20;
+    int z;
     RansState ransN[32] __attribute__((aligned(64)));
 
     if (in_size < 32) // force O0 instead
diff --git a/htscodecs/rANS_static32x16pr_neon.c b/htscodecs/rANS_static32x16pr_neon.c
index 6bd3d41..f658f37 100644
--- a/htscodecs/rANS_static32x16pr_neon.c
+++ b/htscodecs/rANS_static32x16pr_neon.c
@@ -84,7 +84,8 @@ unsigned char *rans_compress_O0_32x16_neon(unsigned char *in,
     uint8_t* ptr;
     uint32_t F[256+MAGIC] = {0};
     int i, j, tab_size = 0, x, z;
-    int bound = rans_compress_bound_4x16(in_size,0)-20; // -20 for order/size/meta
+    // -20 for order/size/meta
+    uint32_t bound = rans_compress_bound_4x16(in_size,0)-20;
 
     if (!out) {
         *out_size = bound;
@@ -912,7 +913,8 @@ unsigned char *rans_compress_O1_32x16_neon(unsigned char *in,
                                            unsigned int *out_size) {
     unsigned char *cp, *out_end, *out_free = NULL;
     unsigned int tab_size;
-    int bound = rans_compress_bound_4x16(in_size,1)-20, z;
+    uint32_t bound = rans_compress_bound_4x16(in_size,1)-20;
+    int z;
     RansState ransN[NX];
 
     if (in_size < NX) // force O0 instead
diff --git a/htscodecs/rANS_static32x16pr_sse4.c b/htscodecs/rANS_static32x16pr_sse4.c
index e88e5f8..fe0345f 100644
--- a/htscodecs/rANS_static32x16pr_sse4.c
+++ b/htscodecs/rANS_static32x16pr_sse4.c
@@ -215,7 +215,8 @@ unsigned char *rans_compress_O0_32x16_sse4(unsigned char *in,
     uint8_t* ptr;
     uint32_t F[256+MAGIC] = {0};
     int i, j, tab_size = 0, x, z;
-    int bound = rans_compress_bound_4x16(in_size,0)-20; // -20 for order/size/meta
+    // -20 for order/size/meta
+    uint32_t bound = rans_compress_bound_4x16(in_size,0)-20;
 
     if (!out) {
         *out_size = bound;
diff --git a/htscodecs/rANS_static4x16pr.c b/htscodecs/rANS_static4x16pr.c
index 6f66f61..cb4fade 100644
--- a/htscodecs/rANS_static4x16pr.c
+++ b/htscodecs/rANS_static4x16pr.c
@@ -116,7 +116,8 @@ unsigned char *rans_compress_O0_4x16(unsigned char *in, unsigned int in_size,
     uint8_t* ptr;
     uint32_t F[256+MAGIC] = {0};
     int i, j, tab_size = 0, rle, x;
-    int bound = rans_compress_bound_4x16(in_size,0)-20; // -20 for order/size/meta
+    // -20 for order/size/meta
+    uint32_t bound = rans_compress_bound_4x16(in_size,0)-20;
 
     if (!out) {
         *out_size = bound;
@@ -345,7 +346,8 @@ unsigned char *rans_uncompress_O0_4x16(unsigned char *in, unsigned int in_size,
 // 10 bit means smaller memory footprint when decoding and
 // more speed due to cache hits, but it *may* be a poor
 // compression fit.
-int rans_compute_shift(uint32_t *F0, uint32_t (*F)[256], uint32_t *T, int *S) {
+int rans_compute_shift(uint32_t *F0, uint32_t (*F)[256], uint32_t *T,
+                       uint32_t *S) {
     int i, j;
 
     double e10 = 0, e12 = 0;
@@ -353,7 +355,7 @@ int rans_compute_shift(uint32_t *F0, uint32_t (*F)[256], uint32_t *T, int *S) {
     for (i = 0; i < 256; i++) {
         if (F0[i] == 0)
             continue;
-        int max_val = round2(T[i]);
+        unsigned int max_val = round2(T[i]);
         int ns = 0;
 #define MAX(a,b) ((a)>(b)?(a):(b))
 
@@ -414,8 +416,9 @@ unsigned char *rans_compress_O1_4x16(unsigned char *in, unsigned int in_size,
                                      unsigned char *out, unsigned int *out_size) {
     unsigned char *cp, *out_end, *out_free = NULL;
     unsigned int tab_size;
-
-    int bound = rans_compress_bound_4x16(in_size,1)-20; // -20 for order/size/meta
+    
+    // -20 for order/size/meta
+    uint32_t bound = rans_compress_bound_4x16(in_size,1)-20;
 
     if (!out) {
         *out_size = bound;
@@ -1094,9 +1097,14 @@ unsigned char *(*rans_dec_func(int do_simd, int order))
  *
  * Smallest is method, <in_size> <input>, so worst case 2 bytes longer.
  */
-unsigned char *rans_compress_to_4x16(unsigned char *in,  unsigned int in_size,
-                                     unsigned char *out, unsigned int *out_size,
+unsigned char *rans_compress_to_4x16(unsigned char *in, unsigned int in_size,
+                                     unsigned char *out,unsigned int *out_size,
                                      int order) {
+    if (in_size > INT_MAX) {
+        *out_size = 0;
+        return NULL;
+    }
+
     unsigned int c_meta_len;
     uint8_t *meta = NULL, *rle = NULL, *packed = NULL;
     uint8_t *out_free = NULL;
diff --git a/htscodecs/tokenise_name3.c b/htscodecs/tokenise_name3.c
index 5767f70..2497f59 100644
--- a/htscodecs/tokenise_name3.c
+++ b/htscodecs/tokenise_name3.c
@@ -1333,6 +1333,11 @@ uint8_t *tok3_encode_names(char *blk, int len, int level, int use_arith,
                            int *out_len, int *last_start_p) {
     int last_start = 0, i, j, nreads;
 
+    if (len < 0) {
+        *out_len = 0;
+        return NULL;
+    }
+
     // Count lines
     for (nreads = i = 0; i < len; i++)
         if (blk[i] <= '\n') // \n or \0 separated entries
diff --git a/tests/arith_dynamic_test.c b/tests/arith_dynamic_test.c
index 0b4c803..708aa9a 100644
--- a/tests/arith_dynamic_test.c
+++ b/tests/arith_dynamic_test.c
@@ -52,7 +52,7 @@
 // Room to allow for expanded BLK_SIZE on worst case compression.
 #define BLK_SIZE2 ((105LL*BLK_SIZE)/100)
 
-static unsigned char in_buf[BLK_SIZE2+257*257*3];
+static unsigned char *in_buf;
 
 // Max 4GB
 static unsigned char *load(FILE *infp, uint32_t *lenp) {
@@ -87,6 +87,8 @@ int main(int argc, char **argv) {
     struct timeval tv1, tv2, tv3, tv4;
     size_t bytes = 0, raw = 0;
 
+    in_buf = malloc(BLK_SIZE2+257*257*3);
+
 #ifdef _WIN32
         _setmode(_fileno(stdin),  _O_BINARY);
         _setmode(_fileno(stdout), _O_BINARY);
@@ -292,5 +294,7 @@ int main(int argc, char **argv) {
             tv2.tv_usec - tv1.tv_usec,
             (double)bytes / ((long)(tv2.tv_sec - tv1.tv_sec)*1000000 +
                              tv2.tv_usec - tv1.tv_usec));
+
+    free(in_buf);
     return 0;
 }
diff --git a/tests/entropy.c b/tests/entropy.c
index 7cfa26b..5cabc62 100644
--- a/tests/entropy.c
+++ b/tests/entropy.c
@@ -58,7 +58,9 @@
 #include "htscodecs/rANS_static.h"
 #include "htscodecs/rANS_static4x16.h"
 
-#define BLK_SIZE 1024*1024
+#ifndef BLK_SIZE
+#   define BLK_SIZE 1024*1024
+#endif
 
 // Max 4GB
 static unsigned char *load(FILE *infp, uint32_t *lenp) {
diff --git a/tests/fqzcomp_qual_test.c b/tests/fqzcomp_qual_test.c
index d0d92cb..b21d4d2 100644
--- a/tests/fqzcomp_qual_test.c
+++ b/tests/fqzcomp_qual_test.c
@@ -257,8 +257,9 @@ static unsigned char *load(char *fn, size_t *lenp) {
     return data;
 }
 
-#define BLK_SIZE 300*1000000
-//#define BLK_SIZE 100*100000
+#ifndef BLK_SIZE
+#    define BLK_SIZE 300*1000000
+#endif
 
 int count_lines(unsigned char *in, size_t len) {
     size_t i;
@@ -320,7 +321,7 @@ int main(int argc, char **argv) {
     int decomp = 0, vers = 4;  // CRAM version 4.0 (4) or 3.1 (3)
     int strat = 0, raw = 0;
     fqz_gparams *gp = NULL, gp_local;
-    int blk_size = BLK_SIZE; // MAX
+    uint32_t blk_size = BLK_SIZE; // MAX
 
 #ifdef _WIN32
         _setmode(_fileno(stdin),  _O_BINARY);
diff --git a/tests/rANS_static4x16pr_test.c b/tests/rANS_static4x16pr_test.c
index 481d64f..74b6c66 100644
--- a/tests/rANS_static4x16pr_test.c
+++ b/tests/rANS_static4x16pr_test.c
@@ -52,7 +52,7 @@
 // Room to allow for expanded BLK_SIZE on worst case compression.
 #define BLK_SIZE2 ((105LL*BLK_SIZE)/100)
 
-static unsigned char in_buf[BLK_SIZE2+257*257*3];
+unsigned char *in_buf;
 
 // Max 4GB
 static unsigned char *load(FILE *infp, uint32_t *lenp) {
@@ -87,6 +87,8 @@ int main(int argc, char **argv) {
     struct timeval tv1, tv2, tv3, tv4;
     size_t bytes = 0, raw = 0;
 
+    in_buf = malloc(BLK_SIZE2+257*257*3);
+
 #ifdef _WIN32
         _setmode(_fileno(stdin),  _O_BINARY);
         _setmode(_fileno(stdout), _O_BINARY);
@@ -332,5 +334,7 @@ int main(int argc, char **argv) {
             tv2.tv_usec - tv1.tv_usec,
             (double)bytes / ((long)(tv2.tv_sec - tv1.tv_sec)*1000000 +
                              tv2.tv_usec - tv1.tv_usec));
+
+    free(in_buf);
     return 0;
 }
diff --git a/tests/rANS_static_test.c b/tests/rANS_static_test.c
index 72ea4b9..ace4d70 100644
--- a/tests/rANS_static_test.c
+++ b/tests/rANS_static_test.c
@@ -49,7 +49,7 @@
 #endif
 
 // Room to allow for expanded BLK_SIZE on worst case compression.
-#define BLK_SIZE2 ((int)(1.05*BLK_SIZE))
+#define BLK_SIZE2 (1.05*BLK_SIZE)
 
 // Max 4GB
 static unsigned char *load(FILE *infp, uint32_t *lenp) {
@@ -93,7 +93,7 @@ static unsigned char *load(FILE *infp, uint32_t *lenp) {
  */
 int main(int argc, char **argv) {
     int opt, order = 0;
-    unsigned char in_buf[BLK_SIZE2+257*257*3];
+    unsigned char *in_buf = malloc(BLK_SIZE2+257*257*3);
     int decode = 0, test = 0;
     FILE *infp = stdin, *outfp = stdout;
     struct timeval tv1, tv2, tv3;
@@ -286,5 +286,7 @@ int main(int argc, char **argv) {
             tv2.tv_usec - tv1.tv_usec,
             (double)bytes / ((long)(tv2.tv_sec - tv1.tv_sec)*1000000 +
                              tv2.tv_usec - tv1.tv_usec));
+
+    free(in_buf);
     return 0;
 }
diff --git a/tests/tokenise_name3_test.c b/tests/tokenise_name3_test.c
index 5f5365b..f19705e 100644
--- a/tests/tokenise_name3_test.c
+++ b/tests/tokenise_name3_test.c
@@ -55,7 +55,7 @@
 #ifndef BLK_SIZE
 #define BLK_SIZE 1*1024*1024
 #endif
-static char blk[BLK_SIZE*2]; // temporary fix for decoder, which needs more space
+static char *blk;
 
 // Max 4GB
 static unsigned char *load(FILE *infp, uint32_t *lenp) {
@@ -218,8 +218,16 @@ int main(int argc, char **argv) {
         _setmode(_fileno(stdout), _O_BINARY);
 #endif
 
+    // temporary fix for decoder, which needs more space
+    blk = malloc(BLK_SIZE*2);
+
+    int ret;
+
     if (argc > 1 && strcmp(argv[1], "-d") == 0)
-        return decode(argc-1, argv+1);
+        ret = decode(argc-1, argv+1);
     else
-        return encode(argc, argv);
+        ret = encode(argc, argv);
+
+    free(blk);
+    return ret;
 }