diff --git a/ext/pg.c b/ext/pg.c
index 67969b1cd..e6e4ef1ac 100644
--- a/ext/pg.c
+++ b/ext/pg.c
@@ -212,10 +212,10 @@ pg_get_rb_encoding_as_pg_encoding( rb_encoding *enc )
  *
  */
 char *
-pg_rb_str_ensure_capa( VALUE str, long expand_len, char *curr_ptr, char **end_ptr )
+pg_rb_str_ensure_capa( VALUE str, size_t expand_len, char *curr_ptr, char **end_ptr )
 {
-	long curr_len = curr_ptr - RSTRING_PTR(str);
-	long curr_capa = rb_str_capacity( str );
+	size_t curr_len = curr_ptr - RSTRING_PTR(str);
+	size_t curr_capa = rb_str_capacity( str );
 	if( curr_capa < curr_len + expand_len ){
 		rb_str_set_len( str, curr_len );
 		rb_str_modify_expand( str, (curr_len + expand_len) * 2 - curr_capa );
diff --git a/ext/pg.h b/ext/pg.h
index 58fa630d2..825eaf8eb 100644
--- a/ext/pg.h
+++ b/ext/pg.h
@@ -319,7 +319,7 @@ VALUE pg_tmbc_allocate                                 _(( void ));
 void pg_coder_init_encoder                             _(( VALUE ));
 void pg_coder_init_decoder                             _(( VALUE ));
 void pg_coder_compact                                  _(( void * ));
-char *pg_rb_str_ensure_capa                            _(( VALUE, long, char *, char ** ));
+char *pg_rb_str_ensure_capa                            _(( VALUE, size_t, char *, char ** ));
 
 #define PG_RB_STR_ENSURE_CAPA( str, expand_len, curr_ptr, end_ptr ) \
 	do { \
diff --git a/ext/pg_copy_coder.c b/ext/pg_copy_coder.c
index 28bbdab39..6d99d29e4 100644
--- a/ext/pg_copy_coder.c
+++ b/ext/pg_copy_coder.c
@@ -220,7 +220,7 @@ pg_text_enc_copy_row(t_pg_coder *conv, VALUE value, char *out, VALUE *intermedia
 	t_pg_copycoder *this = (t_pg_copycoder *)conv;
 	t_pg_coder_enc_func enc_func;
 	static t_pg_coder *p_elem_coder;
-	int i;
+	long i;
 	t_typemap *p_typemap;
 	char *current_out;
 	char *end_capa_ptr;
@@ -265,7 +265,7 @@ pg_text_enc_copy_row(t_pg_coder *conv, VALUE value, char *out, VALUE *intermedia
 					strlen = RSTRING_LENINT(subint);
 
 					/* size of string assuming the worst case, that every character must be escaped. */
-					PG_RB_STR_ENSURE_CAPA( *intermediate, strlen * 2, current_out, end_capa_ptr );
+					PG_RB_STR_ENSURE_CAPA( *intermediate, (size_t)strlen * 2, current_out, end_capa_ptr );
 
 					/* Copy string from subint with backslash escaping */
 					for(ptr1 = RSTRING_PTR(subint); ptr1 < RSTRING_PTR(subint) + strlen; ptr1++) {
@@ -278,7 +278,7 @@ pg_text_enc_copy_row(t_pg_coder *conv, VALUE value, char *out, VALUE *intermedia
 				} else {
 					/* 2nd pass for writing the data to prepared buffer */
 					/* size of string assuming the worst case, that every character must be escaped. */
-					PG_RB_STR_ENSURE_CAPA( *intermediate, strlen * 2, current_out, end_capa_ptr );
+					PG_RB_STR_ENSURE_CAPA( *intermediate, (size_t)strlen * 2, current_out, end_capa_ptr );
 
 					/* Place the unescaped string at current output position. */
 					strlen = enc_func(p_elem_coder, entry, current_out, &subint, enc_idx);
@@ -365,7 +365,7 @@ static int
 pg_bin_enc_copy_row(t_pg_coder *conv, VALUE value, char *out, VALUE *intermediate, int enc_idx)
 {
 	t_pg_copycoder *this = (t_pg_copycoder *)conv;
-	int i;
+	long i;
 	t_typemap *p_typemap;
 	char *current_out;
 	char *end_capa_ptr;
@@ -409,7 +409,7 @@ pg_bin_enc_copy_row(t_pg_coder *conv, VALUE value, char *out, VALUE *intermediat
 					/* we can directly use String value in subint */
 					strlen = RSTRING_LENINT(subint);
 
-					PG_RB_STR_ENSURE_CAPA( *intermediate, 4 + strlen, current_out, end_capa_ptr );
+					PG_RB_STR_ENSURE_CAPA( *intermediate, (size_t)4 + strlen, current_out, end_capa_ptr );
 					/* 4 bytes length */
 					write_nbo32(strlen, current_out);
 					current_out += 4;
@@ -418,7 +418,7 @@ pg_bin_enc_copy_row(t_pg_coder *conv, VALUE value, char *out, VALUE *intermediat
 					current_out += strlen;
 				} else {
 					/* 2nd pass for writing the data to prepared buffer */
-					PG_RB_STR_ENSURE_CAPA( *intermediate, 4 + strlen, current_out, end_capa_ptr );
+					PG_RB_STR_ENSURE_CAPA( *intermediate, (size_t)4 + strlen, current_out, end_capa_ptr );
 					/* 4 bytes length */
 					write_nbo32(strlen, current_out);
 					current_out += 4;
@@ -553,7 +553,7 @@ pg_text_dec_copy_row(t_pg_coder *conv, const char *input_line, int len, int _tup
 		int found_delim = 0;
 		const char *start_ptr;
 		const char *end_ptr;
-		long input_len;
+		size_t input_len;
 
 		/* Remember start of field on input side */
 		start_ptr = cur_ptr;
@@ -688,7 +688,7 @@ pg_text_dec_copy_row(t_pg_coder *conv, const char *input_line, int len, int _tup
 
 		/* Check whether raw input matched null marker */
 		input_len = end_ptr - start_ptr;
-		if (input_len == RSTRING_LEN(this->null_string) &&
+		if (input_len == (size_t)RSTRING_LEN(this->null_string) &&
 					strncmp(start_ptr, RSTRING_PTR(this->null_string), input_len) == 0) {
 			rb_ary_push(array, Qnil);
 		} else {
@@ -830,7 +830,7 @@ pg_bin_dec_copy_row(t_pg_coder *conv, const char *input_line, int len, int _tupl
 		array = rb_ary_new2(expected_fields);
 
 		for( fieldno = 0; fieldno < nfields; fieldno++){
-			long input_len;
+			int input_len;
 
 			/* read field size */
 			if (line_end_ptr - cur_ptr < 4 ) goto length_error;
diff --git a/spec/pg/type_spec.rb b/spec/pg/type_spec.rb
index ad5e5f9b0..a48e96337 100644
--- a/spec/pg/type_spec.rb
+++ b/spec/pg/type_spec.rb
@@ -1369,6 +1369,13 @@ def expect_deprecated_coder_init
 					expect( v.encoding ).to eq( Encoding::ISO_8859_1 )
 					expect( v ).to eq( "Héllo\n".encode(Encoding::ISO_8859_1) )
 				end
+
+				it "should encode big strings" do
+					n = 1 << 30
+					small = "A" * 100
+					large = "\n".b * n
+					encoder.encode([small, large])
+				end
 			end
 
 			context "with TypeMapByClass" do
@@ -1439,6 +1446,13 @@ def expect_deprecated_coder_init
 					expect( v.encoding ).to eq( Encoding::ISO_8859_1 )
 					expect( v.b ).to eq( "\x00\x01\x00\x00\x00\x05H\xE9llo".b )
 				end
+
+				it "should encode big strings" do
+					n = 2_147_483_644
+					wrapped = ((n + 4 + (1 << 31)) % (1 << 32)) - (1 << 31)
+					s = "A".b * n
+					encoder.encode([s])
+				end
 			end
 
 			context "with TypeMapByClass" do