diff --git a/src/common.jl b/src/common.jl
index 0e1618e2..fe8c3ca5 100644
--- a/src/common.jl
+++ b/src/common.jl
@@ -609,10 +609,11 @@ function colormap_callback(cmap::Symbol)
     cdata = ColorSchemes.colorschemes[cmap]
     (z, minz, maxz) -> begin
         isfinite(z) || return INVALID_COLOR
-        get(
-            cdata,
-            minz == maxz ? zero(z) : (max(minz, min(z, maxz)) - minz) / (maxz - minz),
-        ) |> ansi_color
+        z01 =
+            minz == maxz ? zero(z) :
+            (max(minz, min(z, maxz)) - minz) / (maxz - minz)
+        isfinite(z01) || return INVALID_COLOR
+        ansi_color(get(cdata, z01))
     end::ColorType
 end
 
diff --git a/test/tst_issues.jl b/test/tst_issues.jl
index a65817ea..9fd7318b 100644
--- a/test/tst_issues.jl
+++ b/test/tst_issues.jl
@@ -107,4 +107,13 @@
         p = scatterplot(rand(1) * u"m", rand(1))
         show(devnull, p)
     end
+
+    @testset "Heatmap ±Inf (#378)" begin
+        p = heatmap([1 2; 3 -Inf])
+        show(devnull, p)
+        p = heatmap([-Inf;;])
+        show(devnull, p)
+        p = heatmap([1 2; 3 Inf])
+        show(devnull, p)
+    end
 end