diff --git a/src/physfs.c b/src/physfs.c
index 4c900a9b..8d2b9bbf 100644
--- a/src/physfs.c
+++ b/src/physfs.c
@@ -3199,7 +3199,12 @@ int PHYSFS_stat(const char *_fname, PHYSFS_Stat *stat)
 int __PHYSFS_readAll(PHYSFS_Io *io, void *buf, const size_t _len)
 {
     const PHYSFS_uint64 len = (PHYSFS_uint64) _len;
-    return (io->read(io, buf, len) == len);
+    PHYSFS_sint64 amount_read = io->read(io, buf, len);
+    if (amount_read < 0)
+    {
+        return 0;
+    }
+    return ((PHYSFS_uint64)amount_read == len);
 } /* __PHYSFS_readAll */
 
 
diff --git a/src/physfs_archiver_lec3d.c b/src/physfs_archiver_lec3d.c
index 3d0c5012..764f3e2e 100644
--- a/src/physfs_archiver_lec3d.c
+++ b/src/physfs_archiver_lec3d.c
@@ -291,7 +291,7 @@ static int labLoadEntries(PHYSFS_Io *io, const PHYSFS_uint32 cnt, void *arc)
 	PHYSFS_sint32 readlen;
 	PHYSFS_sint64 savepos;
 	char fn[32];
-	int i;
+	PHYSFS_uint32 i;
 
 	for (i = 0; i < cnt; i++)
 	{
diff --git a/src/physfs_archiver_zip.c b/src/physfs_archiver_zip.c
index 7327a619..89698146 100644
--- a/src/physfs_archiver_zip.c
+++ b/src/physfs_archiver_zip.c
@@ -553,7 +553,7 @@ static PHYSFS_sint64 zip_find_end_of_central_dir(PHYSFS_Io *io, PHYSFS_sint64 *l
      *  and call it a corrupted zipfile.
      */
 
-    if (sizeof (buf) < filelen)
+    if (sizeof (buf) < (PHYSFS_uint64)filelen)
     {
         filepos = filelen - sizeof (buf);
         maxread = sizeof (buf);
diff --git a/src/physfs_byteorder.c b/src/physfs_byteorder.c
index b2d3a2cf..91662242 100644
--- a/src/physfs_byteorder.c
+++ b/src/physfs_byteorder.c
@@ -82,7 +82,12 @@ PHYSFS_sint64 PHYSFS_swapSBE64(PHYSFS_sint64 x) { return x; }
 
 static inline int readAll(PHYSFS_File *file, void *val, const size_t len)
 {
-    return (PHYSFS_readBytes(file, val, len) == len);
+    PHYSFS_sint64 amount_read = PHYSFS_readBytes(file, val, len);
+    if (amount_read < 0)
+    {
+        return 0;
+    }
+    return ((PHYSFS_uint64)amount_read == len);
 } /* readAll */
 
 #define PHYSFS_BYTEORDER_READ(datatype, swaptype) \
@@ -108,9 +113,14 @@ PHYSFS_BYTEORDER_READ(sint64, SBE64)
 PHYSFS_BYTEORDER_READ(uint64, UBE64)
 
 
-static inline int writeAll(PHYSFS_File *f, const void *val, const size_t len)
+static inline int writeAll(PHYSFS_File *file, const void *val, const size_t len)
 {
-    return (PHYSFS_writeBytes(f, val, len) == len);
+    PHYSFS_sint64 amount_written = PHYSFS_writeBytes(file, val, len);
+    if (amount_written < 0)
+    {
+        return 0;
+    }
+    return ((PHYSFS_uint64)amount_written == len);
 } /* writeAll */
 
 #define PHYSFS_BYTEORDER_WRITE(datatype, swaptype) \
diff --git a/src/physfs_platform_posix.c b/src/physfs_platform_posix.c
index 7ba5e107..87ab5dae 100644
--- a/src/physfs_platform_posix.c
+++ b/src/physfs_platform_posix.c
@@ -244,7 +244,7 @@ PHYSFS_sint64 __PHYSFS_platformRead(void *opaque, void *buffer,
     } while ((rc == -1) && (errno == EINTR));
     BAIL_IF(rc == -1, errcodeFromErrno(), -1);
     assert(rc >= 0);
-    assert(rc <= len);
+    assert((PHYSFS_uint64)rc <= len);
     return (PHYSFS_sint64) rc;
 } /* __PHYSFS_platformRead */
 
@@ -263,7 +263,7 @@ PHYSFS_sint64 __PHYSFS_platformWrite(void *opaque, const void *buffer,
     } while ((rc == -1) && (errno == EINTR));
     BAIL_IF(rc == -1, errcodeFromErrno(), rc);
     assert(rc >= 0);
-    assert(rc <= len);
+    assert((PHYSFS_uint64)rc <= len);
     return (PHYSFS_sint64) rc;
 } /* __PHYSFS_platformWrite */
 
diff --git a/src/physfs_platform_unix.c b/src/physfs_platform_unix.c
index f580fda6..b14a0f90 100644
--- a/src/physfs_platform_unix.c
+++ b/src/physfs_platform_unix.c
@@ -278,8 +278,8 @@ char *__PHYSFS_platformCalcBaseDir(const char *argv0)
             /* older kernels don't have /proc/self ... try PID version... */
             const unsigned long long pid = (unsigned long long) getpid();
             char path[64];
-            const int rc = (int) snprintf(path,sizeof(path),"/proc/%llu/exe",pid);
-            if ( (rc > 0) && (rc < sizeof(path)) )
+            const int rc = snprintf(path,sizeof(path),"/proc/%llu/exe",pid);
+            if ( (rc > 0) && (rc < (int)sizeof(path)) )
                 retval = readSymLink(path);
         } /* if */
     } /* if */
diff --git a/test/test_physfs.c b/test/test_physfs.c
index a196c5a0..d90baeb7 100644
--- a/test/test_physfs.c
+++ b/test/test_physfs.c
@@ -981,7 +981,7 @@ static int cmd_cat(char *args)
             for (i = 0; i < rc; i++)
                 fputc((int) buffer[i], stdout);
 
-            if (rc < sizeof (buffer))
+            if (rc < (PHYSFS_sint64)sizeof (buffer))
             {
                 printf("\n\n");
                 if (!PHYSFS_eof(f))
@@ -1257,7 +1257,12 @@ static int cmd_append(char *args)
 
         bw = strlen(WRITESTR);
         rc = PHYSFS_writeBytes(f, WRITESTR, bw);
-        if (rc != bw)
+        if (rc < 0)
+        {
+            printf("Writing failed. Reason: [%s].\n",
+                   PHYSFS_getLastError());
+        }
+        else if ((PHYSFS_uint64)rc != bw)
         {
             printf("Wrote (%d) of (%d) bytes. Reason: [%s].\n",
                    (int) rc, (int) bw, PHYSFS_getLastError());
@@ -1305,7 +1310,12 @@ static int cmd_write(char *args)
 
         bw = strlen(WRITESTR);
         rc = PHYSFS_writeBytes(f, WRITESTR, bw);
-        if (rc != bw)
+        if (rc < 0)
+        {
+            printf("Writing failed. Reason: [%s].\n",
+                   PHYSFS_getLastError());
+        }
+        else if ((size_t)rc != bw)
         {
             printf("Wrote (%d) of (%d) bytes. Reason: [%s].\n",
                    (int) rc, (int) bw, PHYSFS_getLastError());