diff --git a/man/gbz80.7 b/man/gbz80.7
index 139f365a4..a51f1acfd 100644
--- a/man/gbz80.7
+++ b/man/gbz80.7
@@ -1008,11 +1008,6 @@ Cycles: 3
 Bytes: 2
 .Pp
 Flags: None affected.
-.Pp
-This is sometimes written as
-.Ql LDIO [n16],A ,
-or
-.Ql LD [$FF00+n8],A .
 .Ss LDH [C],A
 Copy the value in register
 .Sy A
@@ -1026,8 +1021,6 @@ Bytes: 1
 Flags: None affected.
 .Pp
 This is sometimes written as
-.Ql LDIO [C],A ,
-or
 .Ql LD [$FF00+C],A .
 .Ss LD A,[r16]
 Copy the byte pointed to by
@@ -1066,11 +1059,6 @@ Cycles: 3
 Bytes: 2
 .Pp
 Flags: None affected.
-.Pp
-This is sometimes written as
-.Ql LDIO A,[n16] ,
-or
-.Ql LD A,[$FF00+n8] .
 .Ss LDH A,[C]
 Copy the byte at address
 .Ad $FF00+c
@@ -1084,8 +1072,6 @@ Bytes: 1
 Flags: None affected.
 .Pp
 This is sometimes written as
-.Ql LDIO A,[C] ,
-or
 .Ql LD A,[$FF00+C] .
 .Ss LD [HLI],A
 Copy the value in register
diff --git a/src/asm/lexer.cpp b/src/asm/lexer.cpp
index 9574622d9..161b4b6a5 100644
--- a/src/asm/lexer.cpp
+++ b/src/asm/lexer.cpp
@@ -329,6 +329,8 @@ static std::unordered_map<std::string, int, CaseInsensitive, CaseInsensitive> ke
     {"OPT",           T_(POP_OPT)          },
 };
 
+static auto ldio = keywordDict.find("LDIO");
+
 static bool isWhitespace(int c) {
 	return c == ' ' || c == '\t';
 }
@@ -1168,8 +1170,12 @@ static Token readIdentifier(char firstChar, bool raw) {
 
 	// Attempt to check for a keyword if the identifier is not raw
 	if (!raw) {
-		if (auto search = keywordDict.find(identifier); search != keywordDict.end())
+		if (auto search = keywordDict.find(identifier); search != keywordDict.end()) {
+			if (search == ldio) {
+				warning(WARNING_OBSOLETE, "LDIO is deprecated; use LDH\n");
+			}
 			return Token(search->second);
+		}
 	}
 
 	// Label scopes `.` and `..` are the only nonlocal identifiers that start with a dot
diff --git a/src/asm/parser.y b/src/asm/parser.y
index 40c50a198..f4aae733b 100644
--- a/src/asm/parser.y
+++ b/src/asm/parser.y
@@ -1752,8 +1752,8 @@ cpu_command:
 	| z80_jr
 	| z80_ld
 	| z80_ldd
+	| z80_ldh
 	| z80_ldi
-	| z80_ldio
 	| z80_nop
 	| z80_or
 	| z80_pop
@@ -1947,7 +1947,7 @@ z80_ldd:
 	}
 ;
 
-z80_ldio:
+z80_ldh:
 	Z80_LDH MODE_A COMMA op_mem_ind {
 		$4.makeCheckHRAM();
 
diff --git a/test/asm/deprecated-ldio.asm b/test/asm/deprecated-ldio.asm
new file mode 100644
index 000000000..4c381e4b4
--- /dev/null
+++ b/test/asm/deprecated-ldio.asm
@@ -0,0 +1,31 @@
+SECTION "LDIO", ROM0
+
+	ldh [c], a
+	ldh a, [c]
+	ldh [$11], a
+	ldh a, [$11]
+
+	ld [$ff00+c], a
+	ld a, [$ff00+c]
+	ld [$ff11], a
+	ld a, [$ff11]
+
+	ldio [c], a
+	ldio a, [c]
+	ldio [$ff11], a
+	ldio a, [$ff11]
+
+	LDH [C], A
+	LDH A, [C]
+	LDH [$11], A
+	LDH A, [$11]
+
+	LD [$FF00+C], A
+	LD A, [$FF00+C]
+	LD [$FF11], A
+	LD A, [$FF11]
+
+	LDIO [C], A
+	LDIO A, [C]
+	LDIO [$FF11], A
+	LDIO A, [$FF11]
diff --git a/test/asm/deprecated-ldio.err b/test/asm/deprecated-ldio.err
new file mode 100644
index 000000000..b6c038321
--- /dev/null
+++ b/test/asm/deprecated-ldio.err
@@ -0,0 +1,16 @@
+warning: deprecated-ldio.asm(13): [-Wobsolete]
+    LDIO is deprecated; use LDH
+warning: deprecated-ldio.asm(14): [-Wobsolete]
+    LDIO is deprecated; use LDH
+warning: deprecated-ldio.asm(15): [-Wobsolete]
+    LDIO is deprecated; use LDH
+warning: deprecated-ldio.asm(16): [-Wobsolete]
+    LDIO is deprecated; use LDH
+warning: deprecated-ldio.asm(28): [-Wobsolete]
+    LDIO is deprecated; use LDH
+warning: deprecated-ldio.asm(29): [-Wobsolete]
+    LDIO is deprecated; use LDH
+warning: deprecated-ldio.asm(30): [-Wobsolete]
+    LDIO is deprecated; use LDH
+warning: deprecated-ldio.asm(31): [-Wobsolete]
+    LDIO is deprecated; use LDH
diff --git a/test/asm/deprecated-ldio.out.bin b/test/asm/deprecated-ldio.out.bin
new file mode 100644
index 000000000..12fc9a906
--- /dev/null
+++ b/test/asm/deprecated-ldio.out.bin
@@ -0,0 +1 @@
+âòàðâòêÿúÿâòàðâòàðâòêÿúÿâòàð
\ No newline at end of file