diff --git a/configure.ac b/configure.ac
index a82e721..c256805 100644
--- a/configure.ac
+++ b/configure.ac
@@ -68,7 +68,7 @@ AM_CONDITIONAL(SQL, test x$sql = xtrue)
 AC_SUBST(SQL)
 AC_SUBST(LFLAGS)
 
-CFLAGS="$CFLAGS -Wall -Wstrict-prototypes -Werror"
+CFLAGS="$CFLAGS -Wall -Wstrict-prototypes -Wsign-compare -Werror"
 AS_CASE([$host],
         [*mingw*|*cygwin*], [LDFLAGS="$LDFLAGS -no-undefined"], [])
 AS_CASE([$host],
diff --git a/src/libmdb/catalog.c b/src/libmdb/catalog.c
index 8f3d5a0..af1dd4f 100644
--- a/src/libmdb/catalog.c
+++ b/src/libmdb/catalog.c
@@ -48,7 +48,7 @@ static char *type_name[] = {"Form",
 
 void mdb_free_catalog(MdbHandle *mdb)
 {
-	unsigned int i, j;
+	int i, j;
 	MdbCatalogEntry *entry;
 
 	if ((!mdb) || (!mdb->catalog)) return;
@@ -77,7 +77,7 @@ GPtrArray *mdb_read_catalog (MdbHandle *mdb, int objtype)
 	char obj_flags[256];
 	char obj_props[MDB_BIND_SIZE];
 	int type;
-	unsigned int i;
+	int i;
 	MdbColumn *col_props;
 	int kkd_size_ole;
 
diff --git a/src/libmdb/data.c b/src/libmdb/data.c
index bf0a6f6..1fddee8 100644
--- a/src/libmdb/data.c
+++ b/src/libmdb/data.c
@@ -288,6 +288,10 @@ int mdb_read_row(MdbTableDef *table, unsigned int row)
 		fprintf(stderr, "warning: mdb_find_row failed.\n");
 		return 0;
 	}
+    if (row_size == 0) {
+		fprintf(stderr, "warning: row_size = 0.\n");
+		return 0;
+    }
 
 	delflag = lookupflag = 0;
 	if (row_start & 0x8000) lookupflag++;
@@ -304,8 +308,7 @@ int mdb_read_row(MdbTableDef *table, unsigned int row)
 		return 0;
 	}
 
-	num_fields = mdb_crack_row(table, row_start, row_start + row_size - 1,
-		fields);
+	num_fields = mdb_crack_row(table, row_start, row_size, fields);
 	if (num_fields < 0)
 		return 0;
 	if (!mdb_test_sargs(table, fields, num_fields)) return 0;
@@ -371,7 +374,7 @@ int mdb_read_next_dpg(MdbTableDef *table)
 		}
 
 		table->cur_phys_pg = next_pg;
-		if (mdb->pg_buf[0]==MDB_PAGE_DATA && mdb_get_int32(mdb->pg_buf, 4)==entry->table_pg)
+		if (mdb->pg_buf[0]==MDB_PAGE_DATA && mdb_get_int32(mdb->pg_buf, 4)==(long)entry->table_pg)
 			return table->cur_phys_pg;
 
 		/* On rare occasion, mdb_map_find_next will return a wrong page */
@@ -386,7 +389,7 @@ int mdb_read_next_dpg(MdbTableDef *table)
 	do {
 		if (!mdb_read_pg(mdb, table->cur_phys_pg++))
 			return 0;
-	} while (mdb->pg_buf[0]!=MDB_PAGE_DATA || mdb_get_int32(mdb->pg_buf, 4)!=entry->table_pg);
+	} while (mdb->pg_buf[0]!=MDB_PAGE_DATA || mdb_get_int32(mdb->pg_buf, 4)!=(long)entry->table_pg);
 	/* fprintf(stderr,"returning new page %ld\n", table->cur_phys_pg); */
 	return table->cur_phys_pg;
 }
@@ -426,8 +429,7 @@ mdb_fetch_row(MdbTableDef *table)
 				fmt->row_count_offset);
 			if (table->cur_row >= rows) {
 				table->cur_row = 0;
-				table->cur_pg_num++;
-				if (table->cur_pg_num > pages->len)
+				if (++table->cur_pg_num > (unsigned int)pages->len)
 					return 0;
 			}
 			memcpy(mdb->pg_buf,
@@ -539,7 +541,7 @@ mdb_ole_read_next(MdbHandle *mdb, MdbColumn *col, void *ole_ptr)
 	return len - 4;
 }
 size_t 
-mdb_ole_read(MdbHandle *mdb, MdbColumn *col, void *ole_ptr, int chunk_size)
+mdb_ole_read(MdbHandle *mdb, MdbColumn *col, void *ole_ptr, size_t chunk_size)
 {
 	guint32 ole_len;
 	void *buf;
diff --git a/src/libmdb/dump.c b/src/libmdb/dump.c
index 0ff97f9..050c362 100644
--- a/src/libmdb/dump.c
+++ b/src/libmdb/dump.c
@@ -19,22 +19,24 @@
 #include <ctype.h>
 #include <string.h>
 #include <stdio.h>
+#include <inttypes.h>
 
 #ifdef DMALLOC
 #include "dmalloc.h"
 #endif
 
-void mdb_buffer_dump(const void* buf, int start, size_t len)
+void mdb_buffer_dump(const void* buf, off_t start, size_t len)
 {
 	char asc[20];
-	int j, k;
+	size_t j;
+    int k = 0;
 
 	memset(asc, 0, sizeof(asc));
 	k = 0;
-	for (j=start; j<start+len; j++) {
-		unsigned int c = ((const unsigned char *)(buf))[j];
+	for (j=0; j<len; j++) {
+		unsigned int c = ((const unsigned char *)(buf))[start+j];
 		if (k == 0) {
-			fprintf(stdout, "%04x  ", j);
+			fprintf(stdout, "%04" PRIu64 "x  ", (uint64_t)(start+j));
 		}
 		fprintf(stdout, "%02x ", (unsigned char)c);
 		asc[k] = isprint(c) ? c : '.';
@@ -48,11 +50,11 @@ void mdb_buffer_dump(const void* buf, int start, size_t len)
 			k = 0;
 		}
 	}
-	for (j=k; j<16; j++) {
-		fprintf(stdout, "   ");
-	}
 	if (k < 8) {
 		fprintf(stdout, " ");
 	}
+	for (; k<16; k++) {
+		fprintf(stdout, "   ");
+	}
 	fprintf(stdout, "  %s\n", asc);
 }
diff --git a/src/libmdb/index.c b/src/libmdb/index.c
index d6e7af4..803fcd0 100644
--- a/src/libmdb/index.c
+++ b/src/libmdb/index.c
@@ -306,7 +306,7 @@ mdb_read_indices(MdbTableDef *table)
 		/* look for index number i */
 		for (j=0; j<table->num_idxs; ++j) {
 			pidx = g_ptr_array_index (table->indices, j);
-			if (pidx->index_type!=2 && pidx->index_num==i)
+			if (pidx->index_type!=2 && (unsigned int)pidx->index_num==i)
 				break;
 		}
 		if (j==table->num_idxs) {
@@ -1132,7 +1132,7 @@ mdb_index_scan_free(MdbTableDef *table)
 
 void mdb_free_indices(GPtrArray *indices)
 {
-	unsigned int i;
+	int i;
 
 	if (!indices) return;
 	for (i=0; i<indices->len; i++)
diff --git a/src/libmdb/map.c b/src/libmdb/map.c
index 5182ffe..a7e32d0 100644
--- a/src/libmdb/map.c
+++ b/src/libmdb/map.c
@@ -108,7 +108,7 @@ mdb_map_find_next_freepage(MdbTableDef *table, int row_size)
 {
 	MdbCatalogEntry *entry = table->entry;
 	MdbHandle *mdb = entry->mdb;
-	guint32 pgnum;
+	gint32 pgnum;
 	guint32 cur_pg = 0;
 	int free_space;
 
diff --git a/src/libmdb/table.c b/src/libmdb/table.c
index f881756..1e2661c 100644
--- a/src/libmdb/table.c
+++ b/src/libmdb/table.c
@@ -47,7 +47,7 @@ void mdb_free_tabledef(MdbTableDef *table)
 {
 	if (!table) return;
 	if (table->is_temp_table) {
-		unsigned int i;
+		int i;
 		/* Temp table pages are being stored in memory */
 		for (i=0; i<table->temp_table_pages->len; i++)
 			g_free(g_ptr_array_index(table->temp_table_pages,i));
@@ -68,7 +68,7 @@ MdbTableDef *mdb_read_table(MdbCatalogEntry *entry)
 	MdbFormatConstants *fmt = mdb->fmt;
 	int row_start, pg_row;
 	void *buf, *pg_buf = mdb->pg_buf;
-	guint i;
+	int i;
 
 	mdb_read_pg(mdb, entry->table_pg);
 	if (mdb_get_byte(pg_buf, 0) != 0x02)  /* not a valid table def page */
@@ -173,7 +173,7 @@ read_pg_if_n(MdbHandle *mdb, void *buf, int *cur_pos, size_t len)
 		*cur_pos -= (mdb->fmt->pg_size - 8);
 	}
 	/* Copy pages into buffer */
-	while (*cur_pos + len >= mdb->fmt->pg_size) {
+	while (*cur_pos + len >= (size_t)mdb->fmt->pg_size) {
 		int piece_len = mdb->fmt->pg_size - *cur_pos;
 		if (_buf) {
 			memcpy(_buf, mdb->pg_buf + *cur_pos, piece_len);
@@ -198,7 +198,7 @@ void mdb_append_column(GPtrArray *columns, MdbColumn *in_col)
 }
 void mdb_free_columns(GPtrArray *columns)
 {
-	unsigned int i, j;
+	int i, j;
 	MdbColumn *col;
 
 	if (!columns) return;
@@ -220,7 +220,8 @@ GPtrArray *mdb_read_columns(MdbTableDef *table)
 	MdbFormatConstants *fmt = mdb->fmt;
 	MdbColumn *pcol;
 	unsigned char *col;
-	unsigned int i, j;
+	unsigned int i;
+    int j;
 	int cur_pos;
 	size_t name_sz;
 	GPtrArray *allprops;
diff --git a/src/libmdb/write.c b/src/libmdb/write.c
index 1a6f455..93ea10f 100644
--- a/src/libmdb/write.c
+++ b/src/libmdb/write.c
@@ -113,7 +113,8 @@ mdb_is_col_indexed(MdbTableDef *table, int colnum)
 }
 
 static int
-mdb_crack_row4(MdbHandle *mdb, int row_start, int row_end, unsigned int bitmask_sz, unsigned int row_var_cols, unsigned int *var_col_offsets)
+mdb_crack_row4(MdbHandle *mdb, unsigned int row_start, unsigned int row_end,
+        unsigned int bitmask_sz, unsigned int row_var_cols, unsigned int *var_col_offsets)
 {
 	unsigned int i;
 
@@ -128,7 +129,8 @@ mdb_crack_row4(MdbHandle *mdb, int row_start, int row_end, unsigned int bitmask_
     return 1;
 }
 static int
-mdb_crack_row3(MdbHandle *mdb, int row_start, int row_end, unsigned int bitmask_sz, unsigned int row_var_cols, unsigned int *var_col_offsets)
+mdb_crack_row3(MdbHandle *mdb, unsigned int row_start, unsigned int row_end,
+        unsigned int bitmask_sz, unsigned int row_var_cols, unsigned int *var_col_offsets)
 {
 	unsigned int i;
 	unsigned int num_jumps = 0, jumps_used = 0;
@@ -177,7 +179,7 @@ mdb_crack_row3(MdbHandle *mdb, int row_start, int row_end, unsigned int bitmask_
  * Return value: number of fields present, or -1 if the buffer is invalid.
  */
 int
-mdb_crack_row(MdbTableDef *table, int row_start, int row_end, MdbField *fields)
+mdb_crack_row(MdbTableDef *table, int row_start, size_t row_size, MdbField *fields)
 {
 	MdbColumn *col;
 	MdbCatalogEntry *entry = table->entry;
@@ -190,9 +192,10 @@ mdb_crack_row(MdbTableDef *table, int row_start, int row_end, MdbField *fields)
 	unsigned int fixed_cols_found, row_fixed_cols;
 	unsigned int col_count_size;
 	unsigned int i;
+    unsigned int row_end = row_start + row_size - 1;
 
 	if (mdb_get_option(MDB_DEBUG_ROW)) {
-		mdb_buffer_dump(pg_buf, row_start, row_end - row_start + 1);
+		mdb_buffer_dump(pg_buf, row_start, row_size);
 	}
 
 	if (IS_JET3(mdb)) {
@@ -274,7 +277,7 @@ mdb_crack_row(MdbTableDef *table, int row_start, int row_end, MdbField *fields)
 			fields[i].siz = 0;
 			fields[i].is_null = 1;
 		}
-		if (fields[i].start + fields[i].siz > row_end + 1) {
+		if ((size_t)(fields[i].start + fields[i].siz) > row_start + row_size) {
 			fprintf(stderr, "warning: Invalid data location detected in mdb_crack_row.\n");
 			g_free(var_col_offsets);
 			return -1;
@@ -580,7 +583,7 @@ mdb_insert_row(MdbTableDef *table, int num_fields, MdbField *fields)
 	MdbCatalogEntry *entry = table->entry;
 	MdbHandle *mdb = entry->mdb;
 	MdbFormatConstants *fmt = mdb->fmt;
-	guint32 pgnum;
+	gint32 pgnum;
 	guint16 rownum;
 
 	if (!mdb->f->writable) {
@@ -682,15 +685,15 @@ mdb_add_row_to_pg(MdbTableDef *table, unsigned char *row_buffer, int new_row_siz
 int 
 mdb_update_row(MdbTableDef *table)
 {
-int row_start, row_end;
-unsigned int i;
-MdbColumn *col;
-MdbCatalogEntry *entry = table->entry;
-MdbHandle *mdb = entry->mdb;
-MdbField fields[256];
-unsigned char row_buffer[4096];
+    int row_start, row_end;
+    unsigned int i;
+    MdbColumn *col;
+    MdbCatalogEntry *entry = table->entry;
+    MdbHandle *mdb = entry->mdb;
+    MdbField fields[256];
+    unsigned char row_buffer[4096];
 	size_t old_row_size, new_row_size;
-unsigned int num_fields;
+    int num_fields;
 
 	if (!mdb->f->writable) {
 		fprintf(stderr, "File is not open for writing\n");
@@ -719,9 +722,10 @@ unsigned int num_fields;
     }
 
 	if (mdb_get_option(MDB_DEBUG_WRITE)) {
+        /*
 		for (i=0;i<num_fields;i++) {
-			//printf("col %d %d start %d siz %d fixed 5d\n", i, fields[i].colnum, fields[i].start, fields[i].siz, fields[i].is_fixed);
-		}
+			printf("col %d %d start %d siz %d fixed 5d\n", i, fields[i].colnum, fields[i].start, fields[i].siz, fields[i].is_fixed);
+		} */
 	}
 	for (i=0;i<table->num_cols;i++) {
 		col = g_ptr_array_index(table->columns,i);
diff --git a/src/sql/mdbsql.c b/src/sql/mdbsql.c
index e5b8b95..24f428f 100644
--- a/src/sql/mdbsql.c
+++ b/src/sql/mdbsql.c
@@ -145,7 +145,7 @@ void mdb_sql_set_maxrow(MdbSQL *sql, int maxrow)
 
 static void mdb_sql_free_columns(GPtrArray *columns)
 {
-	unsigned int i;
+	int i;
 	if (!columns) return;
 	for (i=0; i<columns->len; i++) {
 		MdbSQLColumn *c = (MdbSQLColumn *)g_ptr_array_index(columns, i);
@@ -156,7 +156,7 @@ static void mdb_sql_free_columns(GPtrArray *columns)
 }
 static void mdb_sql_free_tables(GPtrArray *tables)
 {
-	unsigned int i;
+	int i;
 	if (!tables) return;
 	for (i=0; i<tables->len; i++) {
 		MdbSQLTable *t = (MdbSQLTable *)g_ptr_array_index(tables, i);
diff --git a/src/util/mdb-export.c b/src/util/mdb-export.c
index 4f905a9..977c03d 100755
--- a/src/util/mdb-export.c
+++ b/src/util/mdb-export.c
@@ -227,7 +227,7 @@ main(int argc, char **argv)
 	// TODO refactor this into functions
 	if (mdb->default_backend->capabilities & MDB_SHEXP_BULK_INSERT) {
 		//for efficiency do multi row insert on engines that support this
-		unsigned int counter = 0;
+		int counter = 0;
 		while (mdb_fetch_row(table)) {
 			if (counter % batch_size == 0) {
 				counter = 0; // reset to 0, prevent overflow on extremely large data sets.
diff --git a/src/util/mdb-sql.c b/src/util/mdb-sql.c
index 28c8c3e..0279df3 100644
--- a/src/util/mdb-sql.c
+++ b/src/util/mdb-sql.c
@@ -291,7 +291,7 @@ dump_results_pp(FILE *out, MdbSQL *sql)
 	if (headers) {
 		for (j=0;j<sql->num_columns;j++) {
 			sqlcol = g_ptr_array_index(sql->columns,j);
-			if (strlen(sqlcol->name)>sqlcol->disp_size)
+			if (strlen(sqlcol->name)>(size_t)sqlcol->disp_size)
 				sqlcol->disp_size = strlen(sqlcol->name);
 			print_break(out, sqlcol->disp_size, !j);
 		}