diff --git a/src/FileFormats/LP/write.jl b/src/FileFormats/LP/write.jl
index c4d41a8750..e21083b6b5 100644
--- a/src/FileFormats/LP/write.jl
+++ b/src/FileFormats/LP/write.jl
@@ -47,7 +47,7 @@ function _write_function(
     kwargs...,
 )
     is_first_item = true
-    if !iszero(func.constant)
+    if !iszero(func.constant) || isempty(func.terms)
         _print_shortest(io, func.constant)
         is_first_item = false
     end
@@ -77,7 +77,8 @@ function _write_function(
     kwargs...,
 )
     is_first_item = true
-    if !iszero(func.constant)
+    needs_constant = isempty(func.affine_terms) && isempty(func.quadratic_terms)
+    if !iszero(func.constant) || needs_constant
         _print_shortest(io, func.constant)
         is_first_item = false
     end
diff --git a/src/MathOptInterface.jl b/src/MathOptInterface.jl
index a1fca86501..7a90e98bf0 100644
--- a/src/MathOptInterface.jl
+++ b/src/MathOptInterface.jl
@@ -176,7 +176,7 @@ julia> MOI.write_to_file(model, filename; coefficient_type = Int);
 
 julia> print(read(filename, String))
 minimize
-obj:
+obj: 0
 subject to
 Bounds
 2 <= x <= 3
diff --git a/test/FileFormats/LP/test_LP.jl b/test/FileFormats/LP/test_LP.jl
index 9bef8d8718..a2c58dddbf 100644
--- a/test/FileFormats/LP/test_LP.jl
+++ b/test/FileFormats/LP/test_LP.jl
@@ -345,7 +345,7 @@ function test_quadratic_constraint_diag()
     MOI.write_to_file(model, LP_TEST_FILE)
     @test read(LP_TEST_FILE, String) ==
           "minimize\n" *
-          "obj: \n" *
+          "obj: 0\n" *
           "subject to\n" *
           "c: [ 1 x ^ 2 ] <= 1.4\n" *
           "Bounds\n" *
@@ -366,7 +366,7 @@ function test_quadratic_constraint_off_diag()
     MOI.write_to_file(model, LP_TEST_FILE)
     @test read(LP_TEST_FILE, String) ==
           "minimize\n" *
-          "obj: \n" *
+          "obj: 0\n" *
           "subject to\n" *
           "c: 1.3 + 1.1 x + 1.2 y + [ 1.5 x * y ] = 1.5\n" *
           "Bounds\n" *
@@ -388,7 +388,7 @@ function test_quadratic_constraint_complicated()
     MOI.write_to_file(model, LP_TEST_FILE)
     @test read(LP_TEST_FILE, String) ==
           "minimize\n" *
-          "obj: \n" *
+          "obj: 0\n" *
           "subject to\n" *
           "c: -1.1 <= 1.3 + 1.1 x + 1.2 y + [ -1.1 x ^ 2 + 1.5 x * y ] <= 1.4\n" *
           "Bounds\n" *
@@ -417,7 +417,7 @@ function test_write_indicator()
     MOI.write_to_file(model, LP_TEST_FILE)
     @test read(LP_TEST_FILE, String) ==
           "minimize\n" *
-          "obj: \n" *
+          "obj: 0\n" *
           "subject to\n" *
           "c4:  z = 1 -> 2 x <= 0\n" *
           "c1: z = 1 -> x <= 0\n" *
@@ -722,7 +722,7 @@ function test_infinite_interval()
     MOI.add_constraint(model, 1.0 * x, MOI.Interval(3.0, 4.0))
     @test sprint(write, model) ==
           "minimize\n" *
-          "obj: \n" *
+          "obj: 0\n" *
           "subject to\n" *
           "c1: -inf <= 1 x1 <= inf\n" *
           "c2: -inf <= 1 x1 <= 1\n" *
@@ -1849,6 +1849,30 @@ function test_unsupported_kwarg()
     return
 end
 
+function test_empty_function()
+    model = LP.Model()
+    x = MOI.add_variable(model)
+    c = MOI.add_constraint(
+        model,
+        zero(MOI.ScalarAffineFunction{Float64}),
+        MOI.LessThan(1.0),
+    )
+    MOI.set(model, MOI.ConstraintName(), c, "c")
+    d = MOI.add_constraint(
+        model,
+        zero(MOI.ScalarQuadraticFunction{Float64}),
+        MOI.LessThan(1.0),
+    )
+    MOI.set(model, MOI.ConstraintName(), d, "d")
+    io = IOBuffer()
+    write(io, model)
+    seekstart(io)
+    contents = read(io, String)
+    @test occursin("c: 0 <= 1", contents)
+    @test occursin("d: 0 <= 1", contents)
+    return
+end
+
 end  # module
 
 TestLP.runtests()