diff --git a/src/65c02isa.csv b/src/65c02isa.csv
index fcc0591..8162b9b 100644
--- a/src/65c02isa.csv
+++ b/src/65c02isa.csv
@@ -7,7 +7,7 @@ OP_TSB_ZP,"tsb",ZP,2,NULL
 OP_ORA_ZP,"ora",ZP,2,NULL
 OP_ASL_ZP,"asl",ZP,2,NULL
 OP_RMB0_ZP,"rmb0",ZP,2,NULL
-OP_PHP,"php",IMPLIED,1,NULL
+OP_PHP,"php",IMPLIED,1,emul_php
 OP_ORA_IMM,"ora",IMMEDIATE,2,NULL
 OP_ASL,"asl",ACCUMULATOR,1,NULL
 OP_NOPI_C,"nop",IMPLIED,1,NULL
@@ -39,7 +39,7 @@ OP_BIT_ZP,"bit",ZP,2,NULL
 OP_AND_ZP,"and",ZP,2,emul_and
 OP_ROL_ZP,"rol",ZP,2,NULL
 OP_RMB2_ZP,"rmb2",ZP,2,NULL
-OP_PLP,"plp",IMPLIED,1,NULL
+OP_PLP,"plp",IMPLIED,1,emul_plp
 OP_AND_IMM,"and",IMMEDIATE,2,emul_and
 OP_ROL,"rol",ACCUMULATOR,1,NULL
 OP_NOPI_2C,"nop",IMPLIED,1,NULL
diff --git a/src/emulation.c b/src/emulation.c
index 2366c47..4ff5e41 100644
--- a/src/emulation.c
+++ b/src/emulation.c
@@ -85,6 +85,13 @@ emul_pha(rk65c02emu_t *e, void *id, instruction_t *i)
 	stack_push(e, e->regs.A);
 }
 
+/* PHP - push processor flags to stack */
+void
+emul_php(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	stack_push(e, e->regs.P);
+}
+
 /* PLA - pull from stack to accumulator */
 void
 emul_pla(rk65c02emu_t *e, void *id, instruction_t *i)
@@ -95,6 +102,13 @@ emul_pla(rk65c02emu_t *e, void *id, instruction_t *i)
 	instruction_status_adjust_negative(e, e->regs.A);
 }
 
+/* PLA - pull from stack to processor flags */
+void
+emul_plp(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	e->regs.P = stack_pop(e) | P_UNDEFINED;
+}
+
 /* SEC - set the carry flag */
 void
 emul_sec(rk65c02emu_t *e, void *id, instruction_t *i)
diff --git a/src/rk65c02.c b/src/rk65c02.c
index a64ec1b..77be08b 100644
--- a/src/rk65c02.c
+++ b/src/rk65c02.c
@@ -17,6 +17,7 @@ rk65c02_init(bus_t *b)
 
 	e.bus = b;
 	e.state = STOPPED;
+	e.regs.P = P_UNDEFINED;
 
 	return e;
 }
diff --git a/test/Makefile b/test/Makefile
index 86f4e66..afcd293 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -10,6 +10,7 @@ TESTROMS=test_emulation_and_imm.rom \
 	test_emulation_dex.rom test_emulation_dey.rom \
 	test_emulation_inx.rom test_emulation_iny.rom \
 	test_emulation_pha.rom test_emulation_pla.rom \
+	test_emulation_php.rom test_emulation_plp.rom \
 	test_emulation_nop.rom \
 	test_emulation_lda_imm.rom test_emulation_lda_zp.rom \
 	test_emulation_stz_zp.rom
diff --git a/test/test_emulation.c b/test/test_emulation.c
index 7bc4319..ebb5963 100644
--- a/test/test_emulation.c
+++ b/test/test_emulation.c
@@ -224,6 +224,35 @@ ATF_TC_BODY(emul_stack, tc)
 	bus_finish(&b);
 }
 
+ATF_TC_WITHOUT_HEAD(emul_php_plp);
+ATF_TC_BODY(emul_php_plp, tc)
+{
+	rk65c02emu_t e;
+	bus_t b;
+
+	b = bus_init();
+	e = rk65c02_init(&b);
+
+	e.regs.SP = 0xFF;
+	e.regs.P |= P_CARRY|P_ZERO|P_UNDEFINED;
+
+	ATF_REQUIRE(rom_start(&e, "test_emulation_php.rom"));
+
+	ATF_CHECK(e.regs.SP == 0xFE);
+	ATF_CHECK(bus_read_1(e.bus, STACK_END) == (P_CARRY|P_ZERO|P_UNDEFINED));
+
+	/*
+	 * Now let's see if loading back into accumulator works.
+	 */
+	bus_write_1(e.bus, STACK_END, P_CARRY|P_DECIMAL);
+	ATF_REQUIRE(rom_start(&e, "test_emulation_plp.rom"));
+
+	ATF_CHECK(e.regs.SP == 0xFF);
+	ATF_CHECK(e.regs.P == (P_CARRY|P_DECIMAL|P_UNDEFINED));
+
+	bus_finish(&b);
+}
+
 ATF_TP_ADD_TCS(tp)
 {
 	ATF_TP_ADD_TC(tp, emul_and);
@@ -233,7 +262,7 @@ ATF_TP_ADD_TCS(tp)
 	ATF_TP_ADD_TC(tp, emul_lda);
 	ATF_TP_ADD_TC(tp, emul_nop);
 	ATF_TP_ADD_TC(tp, emul_stz);
-
+	ATF_TP_ADD_TC(tp, emul_php_plp);
 	ATF_TP_ADD_TC(tp, emul_stack);
 
 	return (atf_no_error());
diff --git a/test/test_emulation_php.s b/test/test_emulation_php.s
new file mode 100644
index 0000000..2dbbc60
--- /dev/null
+++ b/test/test_emulation_php.s
@@ -0,0 +1,3 @@
+start:  php
+	stp
+
diff --git a/test/test_emulation_plp.s b/test/test_emulation_plp.s
new file mode 100644
index 0000000..212c1fa
--- /dev/null
+++ b/test/test_emulation_plp.s
@@ -0,0 +1,3 @@
+start:  plp
+	stp
+