diff --git a/liblangutil/Scanner.cpp b/liblangutil/Scanner.cpp
index 3463783bf1dc..9b609ceb0565 100644
--- a/liblangutil/Scanner.cpp
+++ b/liblangutil/Scanner.cpp
@@ -596,7 +596,12 @@ void Scanner::scanToken()
 				token = Token::Period;
 			break;
 		case ':':
-			token = selectToken(Token::Colon);
+			// : :=
+			advance();
+			if (m_char == '=')
+				token = selectToken(Token::AssemblyAssign);
+			else
+				token = Token::Colon;
 			break;
 		case ';':
 			token = selectToken(Token::Semicolon);
diff --git a/liblangutil/Token.h b/liblangutil/Token.h
index 6830e6c24747..35d4f76f339d 100644
--- a/liblangutil/Token.h
+++ b/liblangutil/Token.h
@@ -140,6 +140,8 @@ namespace langutil
 	T(Dec, "--", 0)                                                    \
 	K(Delete, "delete", 0)                                             \
 	\
+	/* Inline Assembly Operators */                                    \
+	T(AssemblyAssign, ":=", 2)                                         \
 	/* Keywords */                                                     \
 	K(Anonymous, "anonymous", 0)                                       \
 	K(As, "as", 0)                                                     \
diff --git a/libyul/AsmParser.cpp b/libyul/AsmParser.cpp
index 217c838a712b..993bf3d3e131 100644
--- a/libyul/AsmParser.cpp
+++ b/libyul/AsmParser.cpp
@@ -158,43 +158,49 @@ Statement Parser::parseStatement()
 		}
 		while (currentToken() == Token::Comma);
 
-		expectToken(Token::Colon);
-		expectToken(Token::Assign);
+		expectToken(Token::AssemblyAssign);
+
+		assignment.value.reset(new Expression(parseExpression()));
+		assignment.location.end = locationOf(*assignment.value).end;
+		return Statement{std::move(assignment)};
+	}
+	case Token::AssemblyAssign:
+	{
+		if (elementary.type() != typeid(Identifier))
+			fatalParserError("Variable name must precede \":=\".");
+
+		Identifier const& identifier = boost::get<Identifier>(elementary);
 
+		Assignment assignment = createWithLocation<Assignment>(identifier.location);
+
+		if (m_dialect->builtin(identifier.name))
+			fatalParserError("Cannot assign to builtin function \"" + identifier.name.str() + "\".");
+		else if (m_dialect->flavour != AsmFlavour::Yul && instructions().count(identifier.name.str()))
+			fatalParserError("Cannot use instruction names for identifier names.");
+
+		advance();
+		assignment.variableNames.emplace_back(identifier);
 		assignment.value.reset(new Expression(parseExpression()));
 		assignment.location.end = locationOf(*assignment.value).end;
 		return Statement{std::move(assignment)};
+
 	}
 	case Token::Colon:
 	{
 		if (elementary.type() != typeid(Identifier))
-			fatalParserError("Label name / variable name must precede \":\".");
+			fatalParserError("Label name must precede \":\".");
+
 		Identifier const& identifier = boost::get<Identifier>(elementary);
+
 		advance();
-		// identifier:=: should be parsed as identifier: =: (i.e. a label),
-		// while identifier:= (being followed by a non-colon) as identifier := (assignment).
-		if (currentToken() == Token::Assign && peekNextToken() != Token::Colon)
-		{
-			Assignment assignment = createWithLocation<Assignment>(identifier.location);
-			if (m_dialect->builtin(identifier.name))
-				fatalParserError("Cannot assign to builtin function \"" + identifier.name.str() + "\".");
-			else if (m_dialect->flavour != AsmFlavour::Yul && instructions().count(identifier.name.str()))
-				fatalParserError("Cannot use instruction names for identifier names.");
-			advance();
-			assignment.variableNames.emplace_back(identifier);
-			assignment.value.reset(new Expression(parseExpression()));
-			assignment.location.end = locationOf(*assignment.value).end;
-			return Statement{std::move(assignment)};
-		}
-		else
-		{
-			// label
-			if (m_dialect->flavour != AsmFlavour::Loose)
-				fatalParserError("Labels are not supported.");
-			Label label = createWithLocation<Label>(identifier.location);
-			label.name = identifier.name;
-			return label;
-		}
+
+		// label
+		if (m_dialect->flavour != AsmFlavour::Loose)
+			fatalParserError("Labels are not supported.");
+
+		Label label = createWithLocation<Label>(identifier.location);
+		label.name = identifier.name;
+		return label;
 	}
 	default:
 		if (m_dialect->flavour != AsmFlavour::Loose)
@@ -439,10 +445,9 @@ VariableDeclaration Parser::parseVariableDeclaration()
 		else
 			break;
 	}
-	if (currentToken() == Token::Colon)
+	if (currentToken() == Token::AssemblyAssign)
 	{
-		expectToken(Token::Colon);
-		expectToken(Token::Assign);
+		expectToken(Token::AssemblyAssign);
 		varDecl.value = make_unique<Expression>(parseExpression());
 		varDecl.location.end = locationOf(*varDecl.value).end;
 	}
diff --git a/test/libsolidity/InlineAssembly.cpp b/test/libsolidity/InlineAssembly.cpp
index 03e74befb580..71850dfb412b 100644
--- a/test/libsolidity/InlineAssembly.cpp
+++ b/test/libsolidity/InlineAssembly.cpp
@@ -682,7 +682,7 @@ BOOST_AUTO_TEST_CASE(inline_assembly_shadowed_instruction_assignment)
 
 BOOST_AUTO_TEST_CASE(inline_assembly_shadowed_instruction_functional_assignment)
 {
-	CHECK_ASSEMBLE_ERROR("{ gas := 2 }", ParserError, "Label name / variable name must precede \":\"");
+	CHECK_ASSEMBLE_ERROR("{ gas := 2 }", ParserError, "Variable name must precede \":=\"");
 }
 
 BOOST_AUTO_TEST_CASE(revert)
diff --git a/test/libsolidity/syntaxTests/inlineAssembly/invalid/missing_variable_in_assign.sol b/test/libsolidity/syntaxTests/inlineAssembly/invalid/missing_variable_in_assign.sol
index c898433340dc..84d72c2d4091 100644
--- a/test/libsolidity/syntaxTests/inlineAssembly/invalid/missing_variable_in_assign.sol
+++ b/test/libsolidity/syntaxTests/inlineAssembly/invalid/missing_variable_in_assign.sol
@@ -7,5 +7,5 @@ contract C {
   }
 }
 // ----
-// ParserError: (87-88): Literal, identifier or instruction expected.
-// ParserError: (87-88): Expected primary expression.
+// ParserError: (87-89): Literal, identifier or instruction expected.
+// ParserError: (87-89): Expected primary expression.
diff --git a/test/libsolidity/syntaxTests/inlineAssembly/invalid/no_identifier_assignment.sol b/test/libsolidity/syntaxTests/inlineAssembly/invalid/no_identifier_assignment.sol
new file mode 100644
index 000000000000..c6a9bfc17f30
--- /dev/null
+++ b/test/libsolidity/syntaxTests/inlineAssembly/invalid/no_identifier_assignment.sol
@@ -0,0 +1,10 @@
+contract C {
+  function f() public pure {
+    assembly {
+      return := 1
+    }
+  }
+}
+// ----
+// ParserError: (70-72): Variable name must precede ":=".
+// ParserError: (70-72): Expected primary expression.
diff --git a/test/libsolidity/syntaxTests/inlineAssembly/invalid/no_identifier_label.sol b/test/libsolidity/syntaxTests/inlineAssembly/invalid/no_identifier_label.sol
new file mode 100644
index 000000000000..b6cd1dff741b
--- /dev/null
+++ b/test/libsolidity/syntaxTests/inlineAssembly/invalid/no_identifier_label.sol
@@ -0,0 +1,10 @@
+contract C {
+  function f() public pure {
+    assembly {
+      return : 1
+    }
+  }
+}
+// ----
+// ParserError: (70-71): Label name must precede ":".
+// ParserError: (70-71): Expected primary expression.
diff --git a/test/libsolidity/syntaxTests/inlineAssembly/invalid/whitespace_in_assignment.sol b/test/libsolidity/syntaxTests/inlineAssembly/invalid/whitespace_in_assignment.sol
new file mode 100644
index 000000000000..e3444b3894fe
--- /dev/null
+++ b/test/libsolidity/syntaxTests/inlineAssembly/invalid/whitespace_in_assignment.sol
@@ -0,0 +1,10 @@
+contract C {
+  function f() public pure {
+    assembly {
+      let x : = mload(0)
+    }
+  }
+}
+// ----
+// ParserError: (69-70): Literal, identifier or instruction expected.
+// ParserError: (69-70): Expected primary expression.
diff --git a/test/libyul/Parser.cpp b/test/libyul/Parser.cpp
index 84f5c14b8df4..1d557047c92f 100644
--- a/test/libyul/Parser.cpp
+++ b/test/libyul/Parser.cpp
@@ -217,7 +217,7 @@ BOOST_AUTO_TEST_CASE(tokens_as_identifers)
 
 BOOST_AUTO_TEST_CASE(lacking_types)
 {
-	CHECK_ERROR("{ let x := 1:u256 }", ParserError, "Expected identifier but got '='");
+	CHECK_ERROR("{ let x := 1:u256 }", ParserError, "Expected ':' but got ':='");
 	CHECK_ERROR("{ let x:u256 := 1 }", ParserError, "Expected ':' but got '}'");
 	CHECK_ERROR("{ function f(a) {} }", ParserError, "Expected ':' but got ')'");
 	CHECK_ERROR("{ function f(a:u256) -> b {} }", ParserError, "Expected ':' but got '{'");