diff --git a/otafault/ota_io.cpp b/otafault/ota_io.cpp
index 02e80f9..2ce3dfc 100644
--- a/otafault/ota_io.cpp
+++ b/otafault/ota_io.cpp
@@ -14,9 +14,7 @@
  * limitations under the License.
  */
 
-#if defined (TARGET_INJECT_FAULTS)
 #include <map>
-#endif
 
 #include <errno.h>
 #include <fcntl.h>
@@ -24,137 +22,128 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
+#include "config.h"
 #include "ota_io.h"
 
-#if defined (TARGET_INJECT_FAULTS)
-static std::map<int, const char*> FilenameCache;
-static std::string FaultFileName =
-#if defined (TARGET_READ_FAULT)
-        TARGET_READ_FAULT;
-#elif defined (TARGET_WRITE_FAULT)
-        TARGET_WRITE_FAULT;
-#elif defined (TARGET_FSYNC_FAULT)
-        TARGET_FSYNC_FAULT;
-#endif // defined (TARGET_READ_FAULT)
-#endif // defined (TARGET_INJECT_FAULTS)
+static std::map<intptr_t, const char*> filename_cache;
+static std::string read_fault_file_name = "";
+static std::string write_fault_file_name = "";
+static std::string fsync_fault_file_name = "";
+
+static bool get_hit_file(const char* cached_path, std::string ffn) {
+    return should_hit_cache()
+        ? !strncmp(cached_path, OTAIO_CACHE_FNAME, strlen(cached_path))
+        : !strncmp(cached_path, ffn.c_str(), strlen(cached_path));
+}
+
+void ota_set_fault_files() {
+    if (should_fault_inject(OTAIO_READ)) {
+        read_fault_file_name = fault_fname(OTAIO_READ);
+    }
+    if (should_fault_inject(OTAIO_WRITE)) {
+        write_fault_file_name = fault_fname(OTAIO_WRITE);
+    }
+    if (should_fault_inject(OTAIO_FSYNC)) {
+        fsync_fault_file_name = fault_fname(OTAIO_FSYNC);
+    }
+}
 
 int ota_open(const char* path, int oflags) {
-#if defined (TARGET_INJECT_FAULTS)
     // Let the caller handle errors; we do not care if open succeeds or fails
     int fd = open(path, oflags);
-    FilenameCache[fd] = path;
+    filename_cache[fd] = path;
     return fd;
-#else
-    return open(path, oflags);
-#endif
 }
 
 int ota_open(const char* path, int oflags, mode_t mode) {
-#if defined (TARGET_INJECT_FAULTS)
     int fd = open(path, oflags, mode);
-    FilenameCache[fd] = path;
-    return fd;
-#else
-    return open(path, oflags, mode);
-#endif
-}
+    filename_cache[fd] = path;
+    return fd; }
 
 FILE* ota_fopen(const char* path, const char* mode) {
-#if defined (TARGET_INJECT_FAULTS)
     FILE* fh = fopen(path, mode);
-    FilenameCache[(intptr_t)fh] = path;
+    filename_cache[(intptr_t)fh] = path;
     return fh;
-#else
-    return fopen(path, mode);
-#endif
 }
 
 int ota_close(int fd) {
-#if defined (TARGET_INJECT_FAULTS)
-    // descriptors can be reused, so make sure not to leave them in the cahce
-    FilenameCache.erase(fd);
-#endif
+    // descriptors can be reused, so make sure not to leave them in the cache
+    filename_cache.erase(fd);
     return close(fd);
 }
 
 int ota_fclose(FILE* fh) {
-#if defined (TARGET_INJECT_FAULTS)
-    FilenameCache.erase((intptr_t)fh);
-#endif
+    filename_cache.erase((intptr_t)fh);
     return fclose(fh);
 }
 
 size_t ota_fread(void* ptr, size_t size, size_t nitems, FILE* stream) {
-#if defined (TARGET_READ_FAULT)
-    if (FilenameCache.find((intptr_t)stream) != FilenameCache.end()
-            && FilenameCache[(intptr_t)stream] == FaultFileName) {
-        FaultFileName = "";
-        errno = EIO;
-        return 0;
-    } else {
-        return fread(ptr, size, nitems, stream);
+    if (should_fault_inject(OTAIO_READ)) {
+        auto cached = filename_cache.find((intptr_t)stream);
+        const char* cached_path = cached->second;
+        if (cached != filename_cache.end() &&
+                get_hit_file(cached_path, read_fault_file_name)) {
+            read_fault_file_name = "";
+            errno = EIO;
+            return 0;
+        }
     }
-#else
     return fread(ptr, size, nitems, stream);
-#endif
 }
 
 ssize_t ota_read(int fd, void* buf, size_t nbyte) {
-#if defined (TARGET_READ_FAULT)
-    if (FilenameCache.find(fd) != FilenameCache.end()
-            && FilenameCache[fd] == FaultFileName) {
-        FaultFileName = "";
-        errno = EIO;
-        return -1;
-    } else {
-        return read(fd, buf, nbyte);
+    if (should_fault_inject(OTAIO_READ)) {
+        auto cached = filename_cache.find(fd);
+        const char* cached_path = cached->second;
+        if (cached != filename_cache.end()
+                && get_hit_file(cached_path, read_fault_file_name)) {
+            read_fault_file_name = "";
+            errno = EIO;
+            return -1;
+        }
     }
-#else
     return read(fd, buf, nbyte);
-#endif
 }
 
 size_t ota_fwrite(const void* ptr, size_t size, size_t count, FILE* stream) {
-#if defined (TARGET_WRITE_FAULT)
-    if (FilenameCache.find((intptr_t)stream) != FilenameCache.end()
-            && FilenameCache[(intptr_t)stream] == FaultFileName) {
-        FaultFileName = "";
-        errno = EIO;
-        return 0;
-    } else {
-        return fwrite(ptr, size, count, stream);
+    if (should_fault_inject(OTAIO_WRITE)) {
+        auto cached = filename_cache.find((intptr_t)stream);
+        const char* cached_path = cached->second;
+        if (cached != filename_cache.end() &&
+                get_hit_file(cached_path, write_fault_file_name)) {
+            write_fault_file_name = "";
+            errno = EIO;
+            return 0;
+        }
     }
-#else
     return fwrite(ptr, size, count, stream);
-#endif
 }
 
 ssize_t ota_write(int fd, const void* buf, size_t nbyte) {
-#if defined (TARGET_WRITE_FAULT)
-    if (FilenameCache.find(fd) != FilenameCache.end()
-            && FilenameCache[fd] == FaultFileName) {
-        FaultFileName = "";
-        errno = EIO;
-        return -1;
-    } else {
-        return write(fd, buf, nbyte);
+    if (should_fault_inject(OTAIO_WRITE)) {
+        auto cached = filename_cache.find(fd);
+        const char* cached_path = cached->second;
+        if (cached != filename_cache.end() &&
+                get_hit_file(cached_path, write_fault_file_name)) {
+            write_fault_file_name = "";
+            errno = EIO;
+            return -1;
+        }
     }
-#else
     return write(fd, buf, nbyte);
-#endif
 }
 
 int ota_fsync(int fd) {
-#if defined (TARGET_FSYNC_FAULT)
-    if (FilenameCache.find(fd) != FilenameCache.end()
-            && FilenameCache[fd] == FaultFileName) {
-        FaultFileName = "";
-        errno = EIO;
-        return -1;
-    } else {
-        return fsync(fd);
+    if (should_fault_inject(OTAIO_FSYNC)) {
+        auto cached = filename_cache.find(fd);
+        const char* cached_path = cached->second;
+        if (cached != filename_cache.end() &&
+                get_hit_file(cached_path, fsync_fault_file_name)) {
+            fsync_fault_file_name = "";
+            errno = EIO;
+            return -1;
+        }
     }
-#else
     return fsync(fd);
-#endif
 }
+